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Plasterboard technical report Recycled plasterboard paper as animal bedding Paper reclaimed from the plasterboard recycling process can be safely used as a bedding material for large animals such as livestock. This report details trials undertaken with dairy cows, a survey of farmer’s requirements for animal bedding, and a demonstration of the economic and practical viability. Recommendations are given for producing and using the material. Project code: PBD0060042 ISBN: 1-84405-314-8 Research date: Dec 2005 – Feb 2007 Date: May 2007

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Page 1: Technical report templates - WRAP - recycled... · plasterboard recycling. One area of its work is to develop markets for the materials from plasterboard recycling (recycled gypsum

Plasterboard technical report

Recycled plasterboard paper as animal bedding

Paper reclaimed from the plasterboard recycling process can be safely used as a bedding material for large animals such as livestock. This report details trials undertaken with dairy cows, a survey of farmer’s requirements for animal bedding, and a demonstration of the economic and practical viability. Recommendations are given for producing and using the material. Project code: PBD0060042 ISBN: 1-84405-314-8 Research date: Dec 2005 – Feb 2007 Date: May 2007

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Front cover photograph: Recycled plasterboard-paper in use as a cubicle bedding material for dairy cows.

The information set out in this report is of a general nature only and not intended to be relied upon in specific cases.

The information does not take account of environmental issues which should be discussed as a matter of routine with the regulatory authorities (the Environment Agency

in England and Wales, the Scottish Environment Protection Agency in Scotland and the Department of the Environment in Northern Ireland).

Consequently, the information contained in this publication is provided only on the condition that WRAP and their sub-contractors will not be liable for any loss, expense or

damage arising from the use or application of such information.

Individuals and organisations proposing to utilise any of the practices and methodologies within this publication are advised to seek appropriate expert professional advice

in respect to their specific situation and requirements.

Any errors or omissions contained within the reports are the responsibility of the respective authors.

For more detail, please refer to WRAP’s Terms & Conditions on its website: www.wrap.org.uk

Published by Waste & Resources The Old Academy Tel: 01295 819 900 Helpline freephone Action Programme 21 Horse Fair Fax: 01295 819 911 0808 100 2040 Banbury, Oxon E-mail: [email protected] OX16 0AH

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Context WRAP WRAP (Waste & Resources Action Programme) works in partnership to encourage and enable businesses and consumers to be more efficient in their use of materials and recycle more things more often. This helps to minimise landfill, reduce carbon emissions and improve our environment. Established as a not-for-profit company in 2000, WRAP is backed by Government funding from Defra and the devolved administrations in Scotland, Wales and Northern Ireland. WRAP and plasterboard Through its Construction Programme, WRAP is helping the construction industry cut costs and increase efficiency through the better use of materials. Plasterboard is used extensively in the construction and refurbishment of buildings as a lining for walls and ceilings, and for forming structures such as partitions. Plasterboard waste can arise on construction sites for a number of reasons, including wasteful design, off-cuts from its installation, damaged boards, and over-ordering. It is estimated that over 300,000 tonnes per year of waste plasterboard is produced on construction sites. It can also arise from strip-out activities during refurbishment and demolition projects; the waste arisings from this source are significantly higher. In total it is estimated that over one million tonnes of waste plasterboard are produced each year from construction and demolition activities. Most of this waste is currently disposed to landfill, even though it can be easily recycled. WRAP receives funding from Defra through the Business Resource Efficiency and Waste (BREW) programme to divert plasterboard waste from landfill by working to overcome the barriers to plasterboard recycling. Additional funding is also received from the devolved administrations in Scotland, Wales and Northern Ireland. WRAP is working to overcome the barriers through the following key areas:

plasterboard waste minimisation;

site waste management;

segregation and collection of plasterboard waste;

development of infrastructure, including waste logistics and recycling capacity;

market development for materials from plasterboard recycling – recycled gypsum and reclaimed paper;

education, awareness and behavioural change; and

informing and influencing legislation, regulations and policy.

More information on WRAP’s work can be found at www.wrap.org.uk/construction

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Recycled plasterboard paper as animal bedding 1

Executive summary Over one million tonnes of waste plasterboard are estimated to be produced each year in the UK from construction and demolition activities. Most of this waste is currently sent to landfill, even though it can easily be recycled. WRAP is working to divert plasterboard waste from landfill by seeking to overcome the barriers to plasterboard recycling. One area of its work is to develop markets for the materials from plasterboard recycling (recycled gypsum and reclaimed paper). This project examined the feasibility of using plasterboard-facing paper reclaimed from the recycling of waste plasterboard, as a bedding material for dairy cows in winter housing. During the winter most dairy farmers in the UK house their cows in cubicle systems; the remainder are housed loose in deep-littered straw yards. Dairy farmers use more than 8,500 tonnes of bedding material every day, equating to around 1.6 million tonnes during a typical winter housing period. Straw, sawdust and sand are the commonest materials; some farmers produce their own straw for bedding but most buy in bedding at a typical cost of around £40/tonne. Waste or recycled materials are increasingly used by farmers as alternative bedding materials. Use of reclaimed paper from plasterboard recycling would provide farmers with further choice and provide plasterboard recyclers with an additional saleable product. There were three key tests in determining the efficacy of waste plasterboard paper as an animal bedding material:

1. Whether farmers would accept it as a bedding material;

2. Its safety (for the cows, farmers and consumers of their milk) and its practical viability of use; and

3. Its economic viability, particularly in comparison with other available bedding materials.

To address these tests, the study consisted of a number of stages: a survey of farmers’ attitudes to animal bedding; development of the trial design; material processing; a bedding trial at two Yorkshire dairy farms; and an economic evaluation. The survey found that farmers considered the key characteristics for bedding were that it was comfortable, dry, absorbent, easy to handle, and kept the cows clean. Price was less of an issue than functionality, suggesting that cost would not be a barrier to the uptake of plasterboard waste as animal bedding provided there were no risks to human and animal health from its use and it met the farmers’ requirements for a bedding material. The next step was to demonstrate the practical viability of the plasterboard waste in a bedding trial. The following parameters were used as the basis of the assessment:

animal condition – cleanliness and teat condition;

milk quality – somatic cell count (SCC), Bactoscan, microbial content, and mineral/heavy metal content;

use of the material; and

manure and slurry handling.

A risk assessment undertaken immediately before the trial began at one of the two participating farms found no problems or unacceptable health and safety issues. Dust masks were worn when bedding up with the paper. The initial trial design had to be amended to incorporate a processing stage to remove unacceptable levels of contamination observed in a sample of plasterboard paper provided by a plasterboard recycler. To accommodate the unforeseen costs of this additional stage, trials were limited to those farms using cubicle housing. The variation in size, density and material of the contaminants made mechanical separation difficult. A mobile separation unit rented from REDOX Recycling Technology successfully removed the small pieces of gypsum, aggregates, screws, nails, dense metal items, wood and heavy plastics present in material supplied by a plasterboard recycler. Remaining contaminants (squashed drinks cans, drinks bottles, pieces of tape measure, plastic banding and sack ties) had to be removed by hand as they had a similar size and density to the paper. The low throughput (4 tonnes/hour) and low yield (58%) meant that the cost of separation was high; once unique costs were removed, processing costs fell to £65/tonne. This cost could be removed altogether if the plasterboard recycler supplying the material ensured contaminants were removed from the waste prior to recycling so they did not end up in the reclaimed paper. Its low density meant that the processed plasterboard

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Recycled plasterboard paper as animal bedding 2

paper had to be transported in moving floor trailers. This cost around £8/tonne plus 8 pence/tonne/mile, giving a competitive cost of £16/tonne for a 100-mile journey. The plasterboard paper bedding was as effective as a straw control in cross-over trials conducted on two dairy farms in south Yorkshire measured in terms of milk quality based on measurements of somatic cell count (SCC) and Bactoscan. Its effectiveness as a clean bedding was confirmed in both scores for leg and flank cleanliness, and scores for teat condition (cleanliness, skin condition and hyperkeratosis). On both counts, cows became progressively cleaner on both the paper and the straw following the onset of winter housing. Tests showed little difference in the average microbial content of milk from cows on paper and on straw. Mineral analysis of the milk showed no difference apart from copper and sulphate levels, which were higher in samples taken while the cows were on paper than on straw. Although the paper had higher levels of heavy metals than straw, these were well below those considered the maximum safe dietary levels. Unlike straw, there was no evidence of the cows eating the paper. After initial wariness of the paper, the cows laid up well on it. For the trials the paper was delivered in bulk, although large bales (250–400kg) would offer logistical advantages. Plasterboard paper requires the same dry storage conditions as straw to be completely effective. The paper bedding can be applied by hand or using a tub bale chopper with reduced blades. Auger spreaders are not suitable for bedding up with the paper. Both farms in the trial were able to use the same slurry management system for the paper bedding as they normally use for straw bedding. Overall farmer reaction was favourable. The trial hosts felt the plasterboard paper worked well and its use would be attractive if the logistics and handling issues on farms could be addressed. The rate of use of plasterboard paper as an animal bedding was effectively double that of straw and four times that of sawdust in terms of weight. Overall use averaged ~1 tonne/cubicle over a 180-day winter housing period. The equivalent value of the plasterboard paper was about half that of straw. The two farms participating in the trial paid £30/tonne for straw, giving an equivalent plasterboard paper value of ~£16/tonne. Compared with the average straw price found in the survey of farmers’ attitudes to bedding, the equivalent price is closer to ~£18/tonne. A significant benefit of the paper bedding being derived from plasterboard was that gypsum powder on the paper increased its ability to absorb water, which meant that it was not necessary for the farmers to add a desiccant such as hydrated lime to the bedding. This reduced time in cleaning the beds, and money. Conclusions The trial demonstrated that clean plasterboard paper is an acceptable alternative to straw as bedding for dairy cows. It should be competitive with straw on price at up to 50% of the market price of straw. The key to establishing plasterboard paper as an animal bedding material will be to supply material free from contaminants in a logistical format complementary to straw. The total UK market for purchased bedding is around 1.1 million tonnes per year. Of this the amount used in cubicle housing is around 780,000 tonnes per year, with a value of £26 million. If plasterboard paper bedding can attain a 5% share of this market it could be worth £1.3 million by supplying around 87,000 tonnes per year. Recommendations Recommendations are provided in the report for:

producers of the plasterboard paper animal bedding;

users of the bedding; and

further development work.

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Recycled plasterboard paper as animal bedding 3

Contents 1.0 Introduction ............................................................................................................................. 5

1.1 Key tests...............................................................................................................................5 1.2 The Dairy Group....................................................................................................................6

2.0 Survey of farmers’ attitudes to animal bedding....................................................................... 7 2.1 Survey respondents ...............................................................................................................7 2.2 Housing details......................................................................................................................7

2.2.1 Cubicle system farms ................................................................................................8 2.2.2 Loose yard farms ......................................................................................................9

2.3 Bedding details......................................................................................................................9 2.3.1 Cubicle system farms ................................................................................................9 2.3.2 Loose yard farms ....................................................................................................10 2.3.3 Estimate of bedding market.....................................................................................11

2.4 Slurry and dung systems......................................................................................................11 2.5 Future considerations ..........................................................................................................12 2.6 Overall conclusion ...............................................................................................................13

3.0 Development of the project ................................................................................................... 14 3.1 Basis of assessment during the bedding trial .........................................................................14

3.1.1 Animal condition .....................................................................................................14 3.1.2 Milk quality .............................................................................................................16 3.1.3 Use of the material .................................................................................................17 3.1.4 Manure and slurry handling .....................................................................................17

3.2 Initial design of the bedding trial ..........................................................................................17 3.3 Risk assessment ..................................................................................................................18 3.4 Preliminary farm visit ...........................................................................................................18 3.5 Amendments to the trial methodology ..................................................................................19 3.6 Sourcing the test material ....................................................................................................19

3.6.1 Product specification ...............................................................................................19 3.6.2 Finding a supplier ...................................................................................................19

3.7 Further revisions to the methodology....................................................................................20 4.0 Material processing................................................................................................................ 21

4.1 Potential processing methodologies ......................................................................................21 4.2 Cost of different options for use of mobile separation unit......................................................22 4.3 Transport logistics ...............................................................................................................23 4.4 Compliance with health and safety requirements ...................................................................24 4.5 Compliance with environmental legislation ............................................................................24 4.6 Results of the refining process..............................................................................................25

4.6.1 Material flows and composition ................................................................................25 4.6.2 Operating options ...................................................................................................27 4.6.3 Analysis of the bedding material ..............................................................................28

4.7 Cost analysis .......................................................................................................................28 5.0 Bedding trial........................................................................................................................... 31

5.1 Trial farms ..........................................................................................................................31 5.2 Pre-trial investigations .........................................................................................................31

5.2.1 Sampling and assessment of the cows and farms......................................................31 5.2.2 Sampling and assessment of the bedding material ....................................................31

5.3 Risk assessment ..................................................................................................................32 5.4 Bedding trial protocol and timescale .....................................................................................33 5.5 Material logistics and handling..............................................................................................35

5.5.1 Supply and storage .................................................................................................35 5.5.2 Making the bed at Farm A .......................................................................................36 5.5.3 Making the bed at Farm B .......................................................................................36 5.5.4 Moisture control......................................................................................................37

5.6 Compliance with health and safety requirements ...................................................................37 5.7 Compliance with environmental legislation ............................................................................37 5.8 Manure management...........................................................................................................37 5.9 Results of the bedding trial ..................................................................................................38

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5.9.1 Animal condition .....................................................................................................38 5.9.2 Milk quality .............................................................................................................40 5.9.3 Mineral and heavy metal content of bedding and milk ...............................................44 5.9.4 Use of the material .................................................................................................45 5.9.5 Manure handling.....................................................................................................46

6.0 Economic evaluation .............................................................................................................. 48 6.1 Bedding material usage........................................................................................................48 6.2 Other cost considerations.....................................................................................................49 6.3 Economic comparison of plasterboard paper and other bedding materials ...............................49 6.4 Transport costs ...................................................................................................................50 6.5 Estimate of market value .....................................................................................................50

7.0 Conclusions ............................................................................................................................ 52 7.1 Farm attitude survey............................................................................................................52 7.2 Development of the trial ......................................................................................................52 7.3 Material processing..............................................................................................................52 7.4 Bedding trial........................................................................................................................53 7.5 Economic evaluation ............................................................................................................54 7.6 Overall................................................................................................................................54

8.0 Recommendations.................................................................................................................. 55 8.1 Producing the material.........................................................................................................55 8.2 Using the material ...............................................................................................................55 8.3 Further development ...........................................................................................................56

9.0 Glossary.................................................................................................................................. 57 Appendix A Laboratory analysis of unprocessed plasterboard paper material ................................. 58 Appendix B Laboratory analysis of processed bedding material....................................................... 59 Appendix C Cow cleanliness scores................................................................................................... 60 Appendix D SCC and Bactoscan results............................................................................................. 61 Appendix E Bacterial analysis of milk................................................................................................ 62 Appendix F Mineral analysis of milk.................................................................................................. 62

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1.0 Introduction The UK currently has around 21,000 registered milk producers with a national herd size of 2 million dairy cows. All the cows require some form of housing during the winter, and two main types are in use. Most dairy farmers house their cows in cubicle systems; the remainder are housed in deep littered straw yards. A wide variety of bedding materials is applied to cubicle beds ranging from chopped straw, sawdust and kiln-dried shavings to washed sand. Inorganic sources of bedding such as sand are increasingly popular as they restrict the growth of microbial pathogens, reduce mastitis infections and improve the health of the dairy cow. The bedding for dairy cows is replenished daily. Depending on the material used, typical application rates are around 3 kg/cow/day in cubicles and 15 kg/cow/day in straw yards. Dairy farmers use more than 8,700 tonnes of bedding material every day, which equates to more than 1.6 million tonnes during a typical winter housing period. Some farmers produce their own straw for bedding, but many rely on purchased bedding which can typically cost in the region of £40/tonne. The total estimated value of the UK market for purchased bedding is therefore over £66 million per year. With reform of the Common Agricultural Policy, the acreage of cereals is likely to fall and less straw will be available. This is increasing the cost of straw, so stimulating the market for alternative bedding materials. Many of the alternative bedding materials available to farmers are based on waste or recycled materials, and can be obtained at a low or competitive price. However, use of materials defined as waste as animal bedding often raises concerns about:

risks to animal welfare; and

farmers using excessive quantities as a way of by-passing regulations on recovering wastes.

When waste plasterboard is recycled, the facing paper and the gypsum core are separated mechanically. The gypsum is crushed and used as a product in various applications, while the paper is usually discarded as a waste. As an alternative and to make use of this paper, many published documents refer to its potential as animal bedding. Indeed, it is known that some farmers in the UK are already using it for this purpose for cattle; some are even circumventing the recycling process and using waste plasterboard directly as a bedding material. However, there are no published studies that evaluate this use – its technical efficacy, animal and user safety, and economic viability – relating to good animal husbandry practice in the UK. This project was therefore undertaken to provide such a study. Should this prove to be a safe and viable use of plasterboard paper, it would benefit farmers by providing an alternative material and benefit plasterboard recyclers by offering an additional saleable product. 1.1 Key tests There were three key tests in determining the efficacy of the plasterboard paper as an animal bedding material:

1. Whether farmers would accept it as a bedding material;

2. Its safety (for the cows, farmers and consumers of the milk) and its practical viability of use; and

3. Its economic viability, particularly in comparison with other available bedding materials.

To address these tests, the study consisted of a number of stages:

a survey of dairy farmers to ascertain bedding practice and their decision-making in choosing materials;

development of a bedding trial;

undertaking a risk assessment to ensure there would be no risk to the health of the animals, farmers or

consumers of the milk;

sourcing material for the trial and ensuring it was fit for use;

the bedding trial and evaluation of the results;

an economic evaluation; and

conclusions and recommendations.

This report presents full details of the various states of the study. Although the study concentrated on dairy cattle, it is possible that the results could be transferred to other large animals.

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1.2 The Dairy Group This project was undertaken by The Dairy Group Ltd, a private company owned by former employees of the ADAS Dairy Group and the preferred supplier to ADAS for dairy consultancy. The Dairy Group provides consultancy for over 500,000 dairy cows in the UK and works internationally providing strategic, business, technical consultancy and training for producers and processors to help them achieve competitive business performance. The main members of the project team were:

Project leader: Nick Holt-Martyn, Operations Director of The Dairy Group Ltd, provides specialist market

analysis and information to The Dairy Group, the Department for Environment, Food and Rural Affairs (Defra)

and ADAS on UK milk production. He is lead adviser to Defra on milk policy and has produced several analyses

for Defra on the impact of the Common Agricultural Policy (CAP) Mid-Term Review on UK dairying and reviews

of the research by Professor Coleman on the future of British dairy farming. Nick has wide practical

experience in dairy systems and management, and has produced many press articles and technical notes. He

was project manager and technical lead on a recent Eurostat project on the harmonisation of milk statistics

with the Phare beneficiary countries.

Dairy hygiene and technology: Ian Ohnstad, is an internationally recognised milking technology consultant

with considerable experience working for commercial companies, non-governmental organisations and

Government departments. His consultancy role covers all aspects of milk harvesting and on-farm milk quality

issues. He also has detailed knowledge of dairy cattle building design and welfare.

Dairy consultant: Terry Rose has over 30 years’ experience advising farmers throughout England and Wales

on technical and business management. His experience of livestock husbandry has been used to deliver

animal welfare advice on behalf of Defra on mastitis, lameness and welfare through the year. Terry currently

provides support to animal health officers investigating animal welfare cases in north-east England.

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2.0 Survey of farmers’ attitudes to animal bedding

This section describes a survey of dairy farmers undertaken to establish the background to their choice of animal bedding as part of an evaluation into the potential role of plasterboard waste as a bedding material for dairy cows. The survey examined:

type, quantity and cost of materials;

choice of bedding system and manure system;

important issues in selecting a material; and

how much farmers were prepared to pay for a material that met all their needs.

The outcomes of the survey set the requirements that plasterboard waste will have to meet if farmers are to be encouraged to use it as a bedding material. Although plasterboard waste would still have to pass risk assessment and evaluation trials, these would focus on meeting the requirements identified by this survey. 2.1 Survey respondents During December 2005 and January 2006, consultants from The Dairy Group surveyed a representative sample of 117 dairy farms in England, Wales and Scotland. The majority of the herds surveyed contained Holstein dairy cattle (84%), with only a moderate influence of the traditional British Friesian breed (13%). Data from the Milk Development Council indicated that, in 2004, the average dairy farm in the UK contained 91 cows with lactation yields of 6634 litres/cow. Over 80% of the survey respondents had more than 100 cows and 28% of the respondents had herds containing more than 200 cows; the average was 160 cows. Milk yields exceeded 7000 litres/cow on 88% of the farms surveyed, with an average of 8100 litres/cow. 2.2 Housing details The survey data were collected and analysed according to the method of housing used. Of the 117 farmers surveyed, 79% (92 farms) housed their dairy cows solely in a cubicle-based system and 9% (11 farms) housed their cows solely in loose yards. The remaining 12% (14 farms) used a combination of both cubicles and loose yards.

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2.2.1 Cubicle system farms There was a range of cubicle partitions on the surveyed farms. The most popular cubicle partition (27%) was the suspended cantilever partition (Figure 1). This partition was followed closely in popularity by the Dutch comfort partition (22%) and the Newton Rigg division (19%). Both the suspended cantilever and Dutch comfort partition are considered to be more suitable for the modern dairy cow; 13% of the surveyed farms were still housing dairy cows with wooden partitions. There was also a range of cubicle dimensions. Cubicle length averaged 2.2m with a clear width between partitions of 1.2m. The current recommendation is that cubicles should be a minimum of 2.4m long, indicating there are still many farms where the cubicle length is inadequate for the modern dairy cow. A brisket board is fitted to the front of a cubicle bed to position the cow when she is laid down. A well-positioned cow will lie for longer and remain cleaner. The risk of mastitis infection will also be significantly reduced. But although this information is well-known within the dairy industry, only 47% of the surveyed farms used a brisket board. A head rail is fitted to the cubicle partition near the front of the cubicle bed to position a cow when she is stood in the cubicle. A much greater number of the farms surveyed (83%) employed a head rail.

Figure 1 Suspended cantilever partitions

The surface of the cubicle on which the cow lies down can be made from a number of products. The most popular cubicle surface was an EVA rubber mat (31%), followed closely by concrete (27%). Both these surfaces require some form of bedding to minimise abrasions to the cow and remove moisture from the cubicle surface. A cubicle bed constructed from washed sand proved popular (21%) among survey respondents; the popularity of this bedding medium is increasing as farmers recognise the importance of a non-organic source of bedding as they seek to reduce udder infections. Proprietary mattresses, which are laid as a seamless carpet and contain a cushioning material, were recorded on 13% of the surveyed farms. Dairy Farm Assurance Schemes and the latest report from the Farm Animal Welfare Council Report on the Welfare of Dairy Cattle, Dec 1997, require that a cubicle-based housing system must always contain more cubicles than cows. This ensures that there is always a space available for a cow to lie down after she has fed or been milked. The current recommendation is that there should always be 5% more cubicle places than cows within a building. The survey results indicated an average occupancy of 94%. However, this masks the range of occupancy results recorded which varied from 73% to 129%.

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2.2.2 Loose yard farms The success of a loose yard housing system (Figure 2) depends, to a significant extent, on the size of the yard and the number of animals accommodated in the yard (stocking rate). If the stocking rate is excessive, animals will become dirty and udder health will deteriorate. The latest British Standard on cattle housing, BS 5502:2005, recommends that a 700kg dairy cow requires 7.0m2 for lying down and an additional 3.0m2 for loafing. The average bedded area for the farms surveyed was 5.5m2/cow. In addition to the bedded area, there was an average loafing area of 2.9m2/cow. This figures represent overstocking of cows in a loose yard system by around 22%.

Figure 2 Loose yard system

2.3 Bedding details 2.3.1 Cubicle system farms All the surveyed farms used some form of bedding on top of the cubicle base whether the base was concrete, an EVA rubber mat or a mattress. The only exception was where the cows were bedded on a sand cubicle; in this case, the construction of the cubicle bed also provided the bedding material in direct contact with the cow. The most popular bedding materials for the cubicle-based systems were cereal straw, rape straw, paper shreds, sand, shavings and sawdust. The amount of bedding material used depended on the nature of the product used. Table 1 shows the relative usage and amounts of different bedding materials. The data are average figures and there was a range of amounts used that varied according to individual farm circumstances. The survey results are broadly in line with the welfare standards used by Defra.

Table 1 Usage and average quantities of bedding materials in cubicle system farms

Bedding material Users Amount used (kg/cow/day)

Cereal straw 40% 2.7

Sawdust 30% 1.4

Sand 22% 8.6

Shavings 3% 0.4

Paper shreds 2% 1.1

Rape straw 2% 1.0

Over half of the farms surveyed (52%) reported using some form of desiccant to dry the back of the cubicles and inhibit bacterial growth. The most popular desiccant was hydrated lime, which was used on 48% of the farms. A further 20% of farms applied a disinfectant to the cubicle beds, either in powder or liquid form, in an attempt to reduce bacterial growth.

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Irrespective of the bedding material used in the cubicles, the majority of farms (61%) applied the bedding from a tractor-mounted machine. Only 34% of farms still applied the bedding by hand. There was some variation in handling the bedding materials. This was driven primarily by the choice of bedding material; 39% of surveyed farms handled the material loose in bulk while 38% preferred large bales. Small bags and small bales accounted for 23% of the farms; such farms predominately bedded using kiln-dried sawdust, which is shrink wrapped into 25kg bales. Only 15% of the farms used home-grown bedding; the rest (85%) of the farms with cubicles purchased their bedding material. The majority of farmers (66%) stored their bedding material within a roofed building. Bedding was stored outside uncovered by 20% of the farms, though these predominately used sand in the cubicles. Under half the farms (44%) applied the bedding material daily, while a small number (14%) applied it twice a day. Less frequent application of bedding, two or three times each week, was associated with the use of sand bedding. Table 2 demonstrated the considerable variation in the cost of cubicle bedding materials. Of the farms surveyed, 57% paid more than £30/tonne for cubicle bedding; the average price was £37/tonne. The average cost of bedding cubicles found in the survey was 9.2 pence/cow/day.

Table 2 Reported costs of bedding materials used in cubicle system farms

Cost of bedding (£/tonne) Percentage of respondents

<10 2

10–20 24

20–30 17

30–40 14

40–50 10

50–60 16

>60 17

2.3.2 Loose yard farms There is currently less scope to use alternative bedding materials in a loose yard system. This is reflected in the survey results; the only bedding materials used were cereal straw (79%), rape straw and sand. The sand was used on one farm in a yard where pregnant animals calve. The majority of the surveyed farms used a cereal straw, typically 12kg of straw/cow/day. Unlike the cubicle-based housing systems, 50% of loose yard systems used no form of desiccant or disinfectant on the bedding material. This reflects the different challenges faced in a loose yard system. Of the farms which employed a desiccant or disinfectant, 33% used hydrated lime while 8% used a liquid disinfectant. Only 33% of the bedding material was applied by hand; the remaining 67% was applied using a machine (tractor mounted or trailed). There was a significant difference between loose yards and cubicles in terms of the source of bedding. Only around 42% of loose yard systems relied on bought-in bedding, while another 16% used a combination of home-grown and purchased bedding. This reflects the utilisation of home-grown cereals on mixed arable/dairy farms. The vast majority of loose yard bedding material was handled in large bales (>300kg). These can be moved mechanically, quickly and efficiently. More than 67% of the farms surveyed stored their bedding under cover; this reflects the cost of the material. The bedding was applied to the loose yard on a daily basis in 67% of the farms.

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The predominate use of cereal straw in loose yards is reflected in the different cost structure for bedding material (Table 3). The average cost of bedding in loose yards was £26/tonne – an average of 27.6 pence/cow/day.

Table 3 Reported costs of bedding materials used in loose yard farms

Cost of bedding (£/tonne) Percentage of respondents

<10 0

10–20 25

20–30 50

30–40 25

40–50 0

50–60 0

>60 0

2.3.3 Estimate of bedding market The UK National herd of dairy cows is approximately 2 million cows. From the survey findings above an estimate can be made of the purchased bedding market (Table 4).

Table 4 Estimate of purchased bedding market

Cubicles Loose yards Total

UK dairy herd 2,000,000

Average bedding use, kg/cow/day 3 12

Average bedding use, t/cow/winter 0.54 2.16

% cows housed in each system 85% 15%

Number of cows 1,700,000 300,000

Total bedding, tonnes 918,000 648,000 1,566,000

% farmers purchase bedding 85% 50%

Purchased bedding market, tonnes 780,300 324,000 1,104,300

Total UK usage of bedding is ~1.57 million tonnes per year. Total UK market for purchased bedding is ~1.1 million tonnes per year. Assuming plasterboard-based bedding is used at the same rate then a 5% market penetration could be ~55,000 tonnes per year 2.4 Slurry and dung systems The choice of the overall bedding system has a profound impact on the method used to store the waste material. Of the farms using a cubicle-based system, 75% relied on either an open slurry lagoon or above ground circular slurry store. The waste product generated by a slurry-based system has a more fluid consistency. It can be handled and stored as a liquid unlike the semi-solid waste material from a loose yard system. The majority of loose yard farms (92%) cleaned out the yard every two to three months. The waste material is removed and either stacked in field heaps for composting and future spreading, or stored in a dung store. Some 22% of the loose yard farms in the survey had a dung store compared with only 3% of cubicle-based system farms.

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2.5 Future considerations Respondents were asked to rank a number of different bedding characteristics according on their importance (Table 5). There was some degree of commonality between the loose yard respondents and the cubicle respondents; characteristics receiving over 50% support are shown in bold.

Table 5 Reported importance of bedding characteristics

Percentage of respondents rating characteristic as highly important

Bedding characteristic

Cubicle system farms Loose yard farms

‘The material must …’

keep cows dry 87 73

keep cows clean 80 73

be comfortable 70 64

absorb moisture 61 64

limit bacterial growth 66 45

fit existing slurry/manure system 76 20

be easy to handle 63 27

be cheap 36 36

be environmentally friendly 16 18

be odour-free 11 9

aid soil structure and fertility 8 9

be dust-free 16 0

Ranking the various bedding characteristics produced some interesting results. Irrespective of the housing system used, it was considered highly important that any bedding material kept cows comfortable and kept cows dry. The material also had to absorb moisture and keep cows clean. It was also considered important that the material limited bacterial growth. The cubicle-based system farmers considered it important that the bedding material was easy to handle and suited the existing slurry system. Only a small number of respondents (36%) considered the cost of the material to be particularly important as long as it met the other criteria. The environmental friendliness of the product was not considered important. Nor was a requirement for the bedding material be dust-free, odour-free or have the ability to improve soil structure or fertility. When asked whether they had considered alternative bedding materials, none of the farmers using loose yards responded positively. This compared with 23% of the cubicle system farmers who said they had considered their use. These farmers reported having considered a number of bedding materials. The most popular of these were straw, sand, sawdust and shavings, but paper shreds, wood chips, MDF chips, plasterboard waste and cardboard shreds were also mentioned. When the farmers were asked directly about the maximum they would be willing to pay for a bedding material, 80% of loose yard farmers said they would not expect to pay more than £30/tonne for a bedding material compared with 58% of cubicle farmers who would pay more than £30/tonne. The response of the loose yard farmers appeared to be influenced by the relatively low cost of cereal straw, the most common material currently used in this type of system.

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2.6 Overall conclusion The survey found that price is less of an issue than functionality suggesting that price should not be an issue to the uptake of plasterboard waste as animal bedding provided waste plasterboard:

passes the risk assessment phases of this project; and

can meet the important requirements discussed in this section.

The overall conclusion is that, provided waste plasterboard passes the evaluations and delivers the requirements established in the survey, there is a potential market of up to 55,500 tonnes per year for a 5% market penetration (based on total UK market for purchased bedding of 1.1 million tonnes, and equivalent bedding usage rate).

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3.0 Development of the project The first test to the viability of plasterboard-based bedding material was whether farmers would accept it. The survey findings (Section 2) indicated that farmers would, in general, consider using a plasterboard-based bedding material as long as it met their requirements. The second test was its practical viability, which would be evaluated through a bedding trial. This section describes:

the criteria to be used to assess the material’s viability during the bedding trial;

the development of the design of the bedding trial;

the elements of the risk assessment; and

sourcing the plasterboard-based bedding material to use in the trial.

3.1 Basis of assessment during the bedding trial In the bedding trial, the practical viability of the plasterboard-based bedding material would be evaluated according to its impact in the following areas:

animal condition;

milk quality;

use of the material; and

manure handling.

The means of evaluating these aspects is detailed below. 3.1.1 Animal condition Assessment of animal conditions has two elements: leg and flank cleanliness, and teat condition. Leg and flank cleanliness The internationally accepted method of assessing cleanliness of dairy cows is the University of Wisconsin-Madison (UW) Scoring System. A score of between 1 and 4 (where 1 is considered ‘clean’ and 4 is considered ‘grossly soiled’) is given for each cow based on a visual assessment of the legs, udder and flanks. The scoring system is illustrated in Figure 3. For the purposes of this study, the cleanliness is expressed as the percentage of the herd having a score of 1 or 2. Teat condition Teat condition is assessed using the system developed by Teat Club International (TCI). This includes the assessment of three aspects: udder cleanliness, teat skin condition, and hyperkeratosis (Table 6).

Table 6 Assessment of teat condition

Parameter Method and scoring

Udder cleanliness A visual assessment of the cleanliness of the udder is made in accordance with the 1–4 scoring system described above. For the purposes of this study, the cleanliness is expressed as the percentage of the herd having a score of 1 or 2.

Teat skin condition A physical examination is made of the teat skin of every cow prior to milking. Teats are handled and scored on a 1–4 scale: smooth teat skin (1), slightly dry teat skin (2), dry teat skin (3) or very dry teat skin (4).

Hyperkeratosis Hyperkeratosis is excessive stimulation of the keratinous lining of the teat canal and is often associated with teat skin dryness. The teat end condition is scored in accordance with the scoring chart shown in Figure 4. For the purposes of this study, good condition is expressed as the percentage of teats in the herd with ‘no ring’ and ‘smooth ring’.

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Figure 3 University of Wisconsin cow cleanliness scoring system

Figure 4 TCI hyperkeratosis scoring system

Score Description Illustration

N No ring The teat-end is smooth with a small, even orifice. This is a typical status for many teats soon after the start of lactation.

S Smooth or Slightly rough ring A raised ring encircles the orifice. The surface of the ring is smooth or it may feel slightly rough but no fronds of old keratin are evident.

R Raised ring A raised, roughened ring with isolated fronds or mounds of old keratin extending 1-3mm from the orifice.

VR Very Rough ring A raised ring with rough fronds or mounds of old keratin extending 4mm or more from the orifice. The rim of the ring is rough and cracked, often giving the teat-end a “flowered” appearance.

Source: Teat club International (TCI)

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3.1.2 Milk quality For routine testing it is standard practice to take samples from the bulk milk, i.e. from the combined milk of the herd at a milking and not from individual cows. Somatic cell count, Bactoscan and microbial content are routinely tested for. As well as demonstrating the safety of the milk for human consumption, they also give an indication of the health of the cows. Somatic cell count (SCC) The somatic cell count is a measure of the number of leucocytes (white blood cells) contained within the milk. The white blood cells are generated by the immune system of the cow in response to a number of challenges including mastitis pathogens. When an animal is challenged by environmental pathogens (such as those found in poor quality or contaminated cow bedding), it is not unusual to see an increase in the SCC of the milk. SCC is measured using a Fossmatic analyser, which stains and then counts the amount of DNA found in a sample of milk. The SCC is reported in thousands/ml. A bulk milk sample with a SCC of <200,000 cells/ml is considered acceptable. Bactoscan score Bactoscan scores are indicative of the bacterial content of a sample of milk. Unlike traditional culturing methods using agar plates, Bactoscan is a rapid test though the results are purely quantitative and give no indication of the type of bacteria contained within the milk. Results are expressed in thousands/ml. A high quality sample would be expected to have a Bactoscan score <20,000 cells/ml. Bacterial content While a Bactoscan score provides an excellent indication of the amount of bacterial contamination in a milk sample, the Bactoscan test is unable to pinpoint the source of the contamination. Differential screening of a bulk milk sample into bacterial types allows the source of contamination to be identified. The bacterial sources will either be from the inside of the udder (mastitis), the outside of the udder (poor teat cleanliness and preparation) or from soiled milking equipment. Mineral and heavy metal content Heavy metals have the potential to be toxic to animals if ingested in concentrations above safe limits. Maximum tolerable levels for heavy metal concentrations in cattle diets have been reported from the USA (Table 7). No equivalent UK guidance could be identified.

Table 7 Maximum tolerable levels for heavy metal concentrations in cattle diets

Heavy metal Maximum tolerable level (ppm)

Cadmium 0.5

Copper 115

Lead 30

Mercury 2

Source: AFES Circular 126, Agricultural & Forestry Experimental Station, University of Alaska Fairbanks Although it was considered unlikely that the cows would eat the plasterboard-based bedding material, it was necessary to test whether it contained heavy metals in concentrations greater than the maximum tolerable levels shown in Table 7. If the cows did ingest heavy metals from the plasterboard metal, there could be potential for harm to the cows and for heavy metals to be transferred to the milk. During the bedding trial, the milk would therefore also be tested for heavy metal concentrations to compare those produced when the cows were on the straw bedding control with levels when on the plasterboard paper bedding. Other metals such as calcium, copper and zinc would also be assessed, along with sulphate, by comparison with concentrations in milk from cows housed on conventional bedding.

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3.1.3 Use of the material During the trial, use of the material would be evaluated objectively through observations by the dairy consultants and feedback from the farmers. Likely aspects included:

the format (e.g. loose, baled, bagged) in which the material is supplied to the farm;

how this format fits in with the format currently used by the farmer (issues relating to storage, handling and

bedding up the cubicles);

health and safety issues associated with using the material;

quantity of material required to make an acceptable bed;

the cows’ reaction to, and acceptance of, the material;

the apparent comfort and suitability of the bed;

the material’s performance in absorbing moisture and urine; and

the farmers’ overall opinion of the material based on their experiences.

3.1.4 Manure and slurry handling Manure and slurry handling would also be evaluated objectively through observations by the dairy consultants and feedback from the farmers involved in the trial. Important aspects included:

the nature of the manure and slurry produced by the soiling of the plasterboard-based bedding;

whether the manure and slurry from the plasterboard-based bedding material could be mucked out of the

cubicles in the same way as manure and slurry from the farmer’s usual bedding material; and

how the manure and slurry performed in the farmer’s existing management system.

3.2 Initial design of the bedding trial It was proposed that the design of the bedding trial would be as follows:

Four suitable dairy farms would be identified. Two farms would have cubicle housing and two farms would

use loose yard housing.

Two bedding materials would be tested: waste plasterboard and reclaimed facing paper. These materials

would be supplied by a plasterboard recycler directly to the farms. The initial design matrix is shown in

Figure 5.

Figure 5 Proposed initial trial design

Farm 1 Farm 2 Farm 3 Farm 4

Straw yard Straw yard Cubicles Cubicles

Reclaimed facing paper Waste plasterboard Reclaimed facing paper Waste plasterboard

The farm, housing and herd would be assessed for condition and cleanliness at the start of the trial, and to

establish the usual housing routine on those farms.

The trial would be a basic cross-over design. Cows would be bedded with the farmer’s usual bedding material

for a period of two weeks and then with the test material for two weeks. This would be repeated for a further

total period of four weeks.

Samples of the bedding materials would be taken for analysis immediately upon delivery.

Milk would be sampled for analysis at the end of each period immediately prior to each changeover of

material.

Cow cleanliness and welfare would be assessed using standard scoring techniques (Section 3.1) immediately

prior to each changeover of material.

The trial was scheduled to run during the winter housing period of 2005-06.

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3.3 Risk assessment A risk assessment would be carried out before the bedding trial began to ensure there would be no risks to:

the cows;

the farmers taking part in the trial; or

consumers of the milk produced during the trial.

The risk assessment was also expected to provide useful information to inform the final methodology for the bedding trial. It would include the following elements:

animal condition (see Section 3.1.1);

sampling and analysis of the milk produced (see Section 3.1.2);

health and safety issues;

the nature of the material supplied;

the methods for storage, handling and bedding up;

general cleanliness of the housing system;

the cow’s acceptance of the material; and

the method of managing the resulting manure or slurry.

3.4 Preliminary farm visit In November 2005, the dairy consultants visited a dairy farm in Somerset with the aim of undertaking the risk assessment. This farm was chosen because it had been using waste plasterboard as a bedding material for its cows in loose yard housing for some time. The supplier of this material to the farm was involved with the project and arranged access. The waste plasterboard varied in appearance and form, but was easily recognisable as crushed plasterboard made from plant off-cuts and broken sheets. Partially separated crushed plasterboard was preferred to whole crushed plasterboard. The cows were found to be bedded on significant quantities of waste plasterboard – estimated to be around 100 kg/cow/day. This was approximately eight times higher than the amount of straw normally used and considered to be far more than necessary to provide an adequate bed. It was understood that the farmer was paid to accept and use the material. The beds were being topped up with a new layer of waste plasterboard each day and then mucked out after 30 days. A thick black leachate was being produced in cracks in the concrete yards and the storage area, which had the characteristic ‘rotten eggs’ smell of hydrogen sulphide. But, overall, the cows were as clean on the waste plasterboard as they would be on straw, despite being in fairly crowded conditions. In addition, the cows were not choosing to lie off the bedded area, which they often do if they are not comfortable with their bed. The milk produced was continuing to be sold and so would have been passing the normal quality testing and farm assurance standards. It was evident that the farm was not suitable for conducting the risk assessment as planned. However, some useful conclusions could be drawn:

Despite the cows appearing not to reject lying on the waste plasterboard, the dairy consultants felt the

material was too rough with hard edges and had too much potential to contain hidden sharp objects to be

used in cubicles, as such aspects could lead to animal injury.

Overuse of waste plasterboard as bedding could lead to the production of high-sulphate leachates and

hydrogen sulphide gas.

Paying a farmer to take the material is likely to lead to overuse. Developing a bedding material that was fit-

for-the purpose might allow it to be sold to farmers at a competitive price. This would lead to it being used in

“normal” quantities suited to good animal husbandry.

The cows were not rejecting use of plasterboard and so there was still potential to develop a bedding material

based on reclaimed plasterboard facing paper.

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There was no indication of milk quality falling below standard.

3.5 Amendments to the trial methodology Following the farm visit, it was decided to make the following amendments to the trial methodology.

The study would concentrate on utilising the reclaimed predominately paper fraction from the plasterboard

recycling process.

The planned risk assessment would be undertaken on one of the farms volunteering for the bedding trial

before this began. If the risk assessment was successful, then the bedding trial could continue straight

afterwards.

The presence of hydrogen sulphide gas in the housing and near the manure/slurry store would be assessed

subjectively; the gas is readily detected by its smell. If any was perceived, then sampling and measurement

would be carried out to quantify it.

3.6 Sourcing the test material 3.6.1 Product specification Based on standard requirements for animal bedding and animal welfare, the bedding material would need to meet the requirements listed in Table 8.

Table 8 Required specification for the bedding material based on plasterboard paper

General A material comprising reclaimed plasterboard paper with some residual gypsum in the form of powder or small particles Consistent in grade and quality throughout the batch delivered

Gypsum particle size Less than 5 mm (note 1)

Gypsum content No maximum (note 2)

Moisture content Less than 15% (note 3)

Other materials None. In particular no sharps, metal objects, glass, wood shards, plastic straps or ties, plastic film or bags, foil or plastic membranes on the paper (note 4)

Chemical contamination

No detectable contamination (e.g. by oils, solvents, wet paint) Heavy metals content within the criteria given in Section 3.1.2 for cattle feed

Note 1 Larger than this can cause discomfort to cows when trodden on. Note 2 Gypsum does not generally pose any hazard to cows or the farmer. At high gypsum contents, however, it is likely to

separate out from the paper and be lost. For the recycler, this is would be wasteful use of a product that has its own market.

Note 3 All bedding should be dry as harmful bacteria require a damp environment to proliferate. Straw bedding typically has a moisture content of 15%. The moisture content can be derived from the percentage dry oven matter.

Note 4 Physical contaminants such as these not only have the potential to cause injury to the cows, but could also create litter when spreading the resulting slurry.

3.6.2 Finding a supplier The supplier of waste plasterboard to the farm visited in November 2005 (Section 3.4) was also supplying farms with plasterboard paper sourced from the recycling operation of a plasterboard manufacturer. It was expected that this paper would be free of contaminants and thus ideal for use in the bedding trial. Unfortunately, this supplier withdrew from involvement in the project. A second supplier of plasterboard paper was identified. This company was an independent plasterboard recycler that accepts waste plasterboard from numerous sources (mainly construction and demolition sites). It produces recycled gypsum as a product and seeks viable markets for the reclaimed facing paper. Unfortunately, the nature of the sources of the waste plasterboard and the design of the recycling facility primarily to produce recycled gypsum meant that the paper stream contained a high proportion of physical contaminants. However, the company could see the potential of the market for suitable reclaimed paper as animal bedding and so was willing to investigate adapting its facility to produce such a product. Processes were successfully included to separate

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large contaminants from the paper stream, but there were still concerns about small pieces of metal (screws and nails) working through the process. The company therefore undertook to fit magnetic extraction equipment to remove these and produce a safe material. During this time, another independent plasterboard recycler came forward willing to be involved in the trial. This third supplier used a different process to the second supplier (details not available), and the reclaimed paper had a different shred size and quantity of residual gypsum. There would thus be benefits in including both sources of paper in the bedding trial. So rather than testing and comparing waste plasterboard and reclaimed paper, it was decided that the bedding trial would test and compare the two paper types as this could provide useful data to inform an optimum specification for the material as animal bedding. Unfortunately, the second supplier then decided to withdraw from the project. The third company was disposing of its waste paper by transferring it to a commercial composting operation. There it was mixed with source-segregated household green waste from a local authority kerbside collection, composted and spread to land under waste management licensing exemptions. A small sample (approx 0.5 kg) of the waste paper was provided to the project team. This sample contained a range of physical contaminants of the type mentioned previously and some relatively large pieces of gypsum. To quantify the contamination in the paper, the dairy consultants visited the composting site where there was a stockpile of the paper material waiting to enter the composting process. This stockpile showed significant contamination with:

metal (drinks cans, screws, nails, miscellaneou s metals);

plastics (bags, tie bands, bottles, ties);

wood (shards of pallet, battens); and

aggregates (large pieces of plasterboard, brick, stone, concrete, gypsum).

A sample from the stockpile on a cubicle bed was shown to a local dairy farmer. He was concerned about the contaminants present and declined to participate in the bedding trial. This indicated that the level of contamination was likely to severely limit uptake of this material as bedding, even if farmers agreed to participate in the bedding trial. The project team therefore decided that the paper material in its current form was unsafe to test as a bedding material. The recycling process used by the third supplier could not be altered easily just to produce material of suitable quality for the purposes of this project. It therefore realised that, for the project to continue, the material would need to be processed separately to remove the contaminants from the supplier’s waste paper stream. 3.7 Further revisions to the methodology As a result of the development work, further amendments were made to the project.

Instead of the trial bedding material being transported directly to the trial farms from the plasterboard

recycling process, an intermediate processing stage would be introduced to ensure the material met the

required specification and was safe to use.

This processing stage would form a new distinct stage in the project. Because the total project budget was

fixed, the costs for this new stage would be met by dropping the trials in loose yard housing and undertaking

them only in cubicle housing. This was deemed the most pragmatic approach as the farmer attitude survey

(Section 2) showed that the largest potential market for the bedding material was with farmers who used

cubicle housing.

The processing stage would take place during autumn 2006, with the bedding trial occurring during

subsequent winter housing period in late 2006.

Section 4 describes the processing stage. The final methodology used for the bedding trial is detailed in Section 5.

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4.0 Material processing

During development work (Section 3), it became clear that processing of the plasterboard-paper material would be required to make it fit for use in the bedding trial. A range of processing options was considered from large material recovery facilities (MRFs) to hand-picking tables, although problems of availability and the limited size of the project proved obstacles. Each option was examined for:

likely success given the broad nature of the contamination; and

potential costs to try to establish cost benefit.

This section describes the potential options, the challenges overcome, the efficiency of the chosen process and an economic evaluation of its success. 4.1 Potential processing methodologies Visual analysis of the sample of plasterboard paper material delivered to the composting site (see Section 3.6.2) revealed that it contained a significant proportion of acceptable gypsum particles (<5 mm) and paper shreds. There was also a visible level of unacceptable gypsum/aggregate particles (>5 mm), metals (screws, nails, cans, construction material), plastics (bags, ties, bands, bottles) and wood (shards of pallet and battens). The challenge was to remove the unacceptable materials despite the range in material, density and size. The combined processing stages would need to achieve the separation of the raw material shown in Figure 6. Following extensive research it became apparent that the widely available separation methods of screens/sieves, magnets, wind shifters and sorting tables would be unable to complete the process as separate individual methods. A combination process would be required.

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Figure 6 Material flow

Discussions with MRF operators suggested that the required separation would be possible with a fixed plant process, but they were unwilling to handle the relatively small quantity required for the trial. A visit to a new MRF demonstrated the separation potential of the process but it had just begun a large local authority contract and could not accommodate the project. Managers thought that their size of plant could process more than 200 tonnes/day and would include separating trommels, wind shifters and a sorting table. Discussions with other MRF operators revealed that all current plant was working at full capacity and was therefore unavailable for the project. This meant that contracting out the refining process to a MRF was not an option. Further discussions with the operator of the new MRF revealed the availability of mobile separating machinery that could provide scaled-down features of the fixed plant. Its machinery supplier, REDOX Recycling Technology B.V. (based in the Netherlands), offered mobile demonstration plant that could be used for the purpose. REDOX was contacted to enquire about machine availability and obtain a quote for hiring the machine. The machine would meet the above specification and could achieve a potential processing rate of 25 tonnes/hour. Given the large variety of contaminants in the material, the use of hand-picking tables was considered as an alternative to mechanical separation. But hand-picking was felt to be an inferior option due to the limited level of throughput, difficulty of removing small contaminant particles, staffing costs and training need. It was therefore decided to pursue use of the mobile separation unit supplied by REDOX. 4.2 Cost of different options for use of mobile separation unit Having decided to use the mobile separation unit the project team decided that undertaking the processing itself would be more appropriate than contracting-out the process to a third party to undertake the labour. This was due to:

the novel nature of the process;

the need for the project team to provide a quality control function; and

tight timescale and budget requirements for this project stage.

The composting site used by the third recycler agreed to be involved in the project and:

host the mobile separating machinery temporarily;

deal with any unused and waste materials through its normal composting, recycling and waste disposal

outlets; and

provide additional labour if necessary to assist the processing.

Paper

Non-paper items

< 5 mm gypsum particles

> 5 mm gypsum particles

Raw material

Bedding

Waste

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Table 9 shows the budgeted costs for this processing stage. These are based on 150 tonnes of material being processed, of which an estimated 25% would not be suitable for bedding and so be composted, and 10% be contaminants for recycling or disposal. 97.5 tonnes of bedding material was therefore estimated. The 25 tonnes/hour potential processing rate suggested that this could be undertaken in around six hours. However, to allow for setting-up, occasional adjustment, and cleaning at the end, it was assumed the machine would be hired for two days.

Table 9 Budgeted costs for processing 150 tonnes of material using the REDOX mobile unit*

Item £/tonne £

Transport to facility 10 1500

Facility gate fee 5 750

REDOX machine rental 14 3800

Additional labour 3 1193

Composting unsuitable material (25%) 15 562

Disposal of waste (10%) 25 375

Contingency (10%) - 648

Total - 8828

Cost per tonne 58.85 Cost per tonne for 97.5t processed material

90.54

* Costs excluding VAT 4.3 Transport logistics The plasterboard paper material was transported from the plasterboard recycling facility to the composting site as there was insufficient space at the recycling facility to accommodate the REDOX equipment. Previous transport of plasterboard paper for composting indicated that loads weighed only 15 tonnes, indicating a significant transport issue. Due to the low material density, normal aggregate transport companies declined to quote for the job suggesting that a moving floor trailer would be required to achieve the bulk and hence the weight per load. The moving floor would also allow an element of compaction of the load. A haulage contractor with articulated walking floor trailers was located who suggested a potential load size of 25 tonnes might be possible. As the density problem would also be present in the processed material, the contractor was also contracted to transport the bedding material from the composting site to one of the trial farms. The haulage contractor was a registered waste carrier. Table 10 shows the estimated transport costs of the trial. Based on this transport pricing model, transporting bedding material to the dairy areas of the UK from south-east England (say 200 miles) would cost £600 or £24/tonne.

Table 10 Estimated transport costs for plasterboard paper material

Transport costs of 25-tonne load ~£8/tonne + 8 pence/tonne/mile

Distance between recycling facility and composting site 64 miles

Nominal total cost for 25-tonne load ~£328 or £13/tonne

Distance between composting site and trial farms 126 miles

Nominal total cost for 25-tonne load ~£452 or £18/tonne

Alternatives to bulk transport were considered involving baling or bagging by hiring appropriate equipment.

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Investigations revealed that small industrial balers (<250kg) were available to hire, but the throughput was likely to be lower than that expected from the refining process. Larger balers (250–500kg), which would have complemented agricultural bedding handling systems, were not available in a mobile form. Discussions with the plasterboard recycler on bagging indicated that the low density of the material meant it became impractical due to the expected processing rate. On balance, bulk transport was chosen as it was likely to be more cost-effective and efficient. 4.4 Compliance with health and safety requirements Waste plasterboard material is non-hazardous, though handling can give rise to a significant dust issue and an unpleasant working environment. Although gypsum dust is inert, it is hygroscopic and thus readily absorbs moisture from the atmosphere. The following precautions were taken to comply with safe working practices of The Dairy Group:

high-visibility waistcoat (EN 471 Class 2);

hard hat (EN 397);

general purpose gloves;

standard dust mask (EN 149:2001 FFP2); and

safety glasses (EN 166/EN 170).

Staff from The Dairy Group were briefed by the REDOX site engineer on:

the hazards relating to working close to the machine;

the need to wear safety clothing at all times;

the need to be aware of the movement of vehicles and loaders; and

the need to take appropriate breaks during the day.

Operating the REDOX machine was the responsibility of the REDOX engineer. 4.5 Compliance with environmental legislation The process was licensed by the Environment Agency as an exempt activity under Schedule 3, paragraph 11 (treatment of wastes intended for recovery) of the Waste Licensing Regulations (as amended).

Figure 7 Main output showing the canvas hood

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The outputs from the process – the processed material and the removed contaminants – were segregated and contained by straw bales to prevent post-processing contamination or loss to the environment. To minimise fugitive escape of dust and material, the working area was enclosed by stacked straw bales and a canvas hood (Figure 7) was attached over the main output chute of the machine. 4.6 Results of the refining process 4.6.1 Material flows and composition A processing rate of up to 25 tonnes/hour had been suggested by REDOX, although it was recognised that this was an experimental process and there would be an element of learning from experience. The resulting material flows were as shown in Table 11.

Table 11 Processed material flows

Tonnes Percentage

Total available for processing 130.8

Unprocessed material 72.5

Total processed 58.3

Waste (graded-out material) (Figure 8) 18.0 31

Waste (contaminants) (Figures 9 and 10) 6.0 10

Total waste 24.0 41

Losses to dust (estimated) 0.8 1

Recovered bedding material 33.5 58 130.8 tonnes was delivered to the facility rather than the 150 tonnes originally estimated. A total of 14.5 hours were spent running the REDOX machine to process 58.3 tonnes (Table 11). 72.5 tonnes of material was therefore not processed, due to lower throughput than expected and a period of down-time while a repair was made to the machine. This gave an actual achieved rate of 4 tonnes/hour material processed and a yield of 2.3 tonnes/hour of recovered bedding material. Running with higher throughputs increased the material presented to the air jet; this reduced the efficiency of separation and thus increased the risk of contaminants appearing in the bedding material. The 15mm screen successfully removed small particles of gypsum and aggregates together with nails, screws and other small metal objects, and small particles of paper (1–5mm). Approximately 18 tonnes (31% of the total processed) of this material was produced. The material that came through the screen was pea-like and gravel-like in appearance (Figure 8).

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Figure 8 Material graded out by the 15mm screen (straw bales in the background)

The remaining material flow was lifted, before dropping vertically through an air jet inclined upwards at 45°, which lifted the lower density particles onto a conveyor. Large pieces of aggregate and metal objects such as reinforcing mesh, ducting, cable and even a whole bag of plaster were removed, leaving a mostly paper stream. Relatively little material – approximately 6 tonnes (10% of the total processed) – was removed at this stage, the material removed was of a high contaminant nature (Figure 9).

Figure 9 High density contaminants removed from the material

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The plasterboard paper material still contained some contaminants. These were low density items including plastic bags, tie bands, plastic drinks bottles, drinks cans, wire, small wood pieces, plastic ties and pieces of tape measure (Figure 10). The REDOX machine could not remove these as they were too similar to the plasterboard paper and so they were removed by hand in a final quality control.

Figure 10 Low density contaminants removed from the material

The resulting material was loose. It contained particles of gypsum and gypsum dust, and looked ideal as bedding material. One operator reported sensing the skin irritation of mineral fibres, although none were actually seen or removed. The unprocessed material (72.5 tonnes) was composted at the site as usual. The graded-out gypsum was disposed of by the composter by spreading on arable land, and the waste objects were disposed of with similar materials from the composting process. The processing yielded 33.5 tonnes (58%) of bedding material (Figure 11), which was transported to one of the farms (Farm A) ready for the bedding trials (Section 5).

Figure 11 Processed bedding material

4.6.2 Operating options It had been hoped to re-mix the small particles with the final paper material to increase the yield of bedding material. However, the presence of nails and screws in the <15 mm fraction prevented blending. A smaller screen size (5mm) could have excluded the nails, but would have increased the material flow to the windshifter and thus reduced the processing rate further. Alternatively a magnet could have been used to remove most of the nails and screws, allowing the small material into the bedding stream.

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A larger screen size could have been used to reduce the material presented to the windshifter, allowing an increased processing rate. However, this would have resulted in the loss of one hour of processing time and increased the risk of large gypsum lumps being present in the final paper material. It was therefore decided to continue with the machine in its original set-up. The alternative to the wind shifter would be to use a trommel to remove all particles below 40 mm, with the final paper stream being passed over a sorting table to remove the larger objects by hand. A hand-sorting table had originally been considered in combination with a mechanical process, but it was not possible for a small experimental quantity. Although some human sorting was carried out on the final paper flow, this could have been improved using a sorting table and would be an option for any future commercial process. 4.6.3 Analysis of the bedding material Laboratory analysis of the plasterboard paper material before and after processing included a determination of total ash in each sample, which is the dry residue left after the sample has been fully burnt. This would comprise mainly gypsum, some ash from combustion of the paper, and a very small amount of non-combustable contaminants such as aggregate fines. It is estimated that gypsum has an ash content of 95% and paper an ash content of 12%. Analysis of the unprocessed plasterboard paper material (Table 12) shows an ash content of 59.8%, and the processed material an ash content of 24.4%. It can therefore be calculated that the processing reduced the gypsum content in the material from approximately 58% to 15%.

Table 12 Results of laboratory analysis*

Determinand Units Unprocessed material Processed material

Oven dry matter (DM) % m/m 65.4 92.3 Total ash g/100 g, 100% DM 59.8 24.4 Total cadmium mg/kg, 100% DM 0.34 <0.10 Total chromium mg/kg, 100% DM 3.61 3.78 Total copper mg/kg, 100% DM 13.6 18.0 Total lead mg/kg, 100% DM 6.22 18.0 Total mercury mg/kg, 100% DM 0.09 0.30 Total nickel mg/kg, 100% DM <2.0 3.0 Total zinc mg/kg, 100% DM 28.7 32.8 * See Appendices A and B for a full reproduction of the results. The low dry matter content of the unprocessed sample (65.4%) was due to rain ingress and outside storage. The processed material had a dry matter content of 92.3% (7.7% moisture content) which, when compared with farm straw at around 85% (15% moisture content), makes it within the specification (Table 7) for a bedding material. The content of lead, nickel, mercury and copper rose during separation suggesting they are part of the paper fraction. Lead and mercury levels rose approximately three-fold during the process. However, all levels are below the maximum tolerable levels for heavy metal concentrations in cattle feed found in the literature (Table 6). 4.7 Cost analysis The experimental nature of the process meant that it was unlikely to deliver economic results without further refinement and investigation. The first priority of the processing was to produce material in suitable amounts and of acceptable quality for use in the bedding trial through mechanical separation. The second was to consider the economics of the process as a means of generating a viable, refined stream of paper bedding from plasterboard waste. Table 13 summarises the actual costs of the processing carried out for the project compared with the original project budget.

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Table 13 Actual processing costs*

Rate (£/item) Total (£) Difference from budget (£)

Transport to facility (five loads @ ~25 tonnes/load)

325.00 1640 140

Facility gate fee 500 -250

REDOX machine rental 3659 -140

Fuel (200 litres) 0.385 77 77

Additional labour 2000 807 Composting unprocessed material (72.5 tonnes)

35.50 2340 1777

Disposal of waste (24 tonnes) 25.00 600 225

Health & safety equipment 26 26

Contingency -685

Total 10,842 +1977 * Costs excluding VAT Many of the costs are unique to the trial and would not occur under operational conditions if the process was carried out by the plasterboard recycler rather than moving the material to a separate site. These unique costs are separated out in Table 14. The overall costs per tonne processed in the project were £186, but these break down to unique costs of £121 and true processing costs of £65/tonne. With only 33.5 tonnes of bedding recovered (i.e. 58%), the true processing costs are £112/tonne of bedding.

Table 14 Separation of costs to determine processing costs

Total (£) Unique costs (£) Processing costs (£)

Transport to facility 1640 1640

Facility gate fee 500 500

REDOX machine rent 3659 3659

Fuel 77 77

Additional labour 2000 2000

Composting unprocessed material 2340 2340

Disposal of waste 600 600

Health & safety equipment 26 26

Total 10,842 7080 3762

Amount of material processed 58.3 tonnes

Cost per tonne £186 £121 £65 Amount of bedding material recovered 33.5 tonnes

Cost per tonne for bedding material £324 £211 £112 Theoretical cost per tonne at 80% recovery £232 £152 £81 Theoretical cost per tonne with 2x throughput and 80% recovery

£116 £76 £40

Throughput was the limiting factor; doubling throughput halves the unit cost. Throughput was hindered by the high gypsum content of the plasterboard paper even though initial separation had occurred at the plasterboard recycling site. A higher degree of primary separation of gypsum from the paper is essential to enable more gypsum to be returned to its own markets. Reducing the gypsum content would have increased the paper content and reduced the density of the material flow, thus aiding separation. The ferrous metal content of the plasterboard paper could also be removed during the initial plasterboard recycling process. This already occurs with the gypsum stream via an over-band magnet but not with the paper stream. An eddy current separator could similarly remove non-ferrous metallic contaminants. Larger metal pieces and non-metallic material should be removed when observed by hand throughout the handling process – this

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begins on the building site and continues to the final destination. This is a quality control issue where incorrect wastes are placed in the plasterboard waste skip. Smaller plastic fractions such as drinks bottles and tie bands should be excluded under the quality control process at building sites. Their size and density are too similar to the paper fraction to facilitate mechanical removal.

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5.0 Bedding trial This section describes trials undertaken to demonstrate the viability of using reclaimed plasterboard paper as a bedding material for livestock. The refining process described in Section 4 produced a plasterboard paper material that was free from injurious contaminants. The material was then suitable for testing against cereal straw and the bedding requirements as found by the farmer attitude survey (Section 2). Two farms with cubicle housing systems that normally used cereal straw volunteered to try the material within a controlled test. The trial involved comparing cow cleanliness and health, milk hygiene and milk heavy metal content while cows were bedded on straw or on the plasterboard paper bedding material. The cross-over design allowed performance of the two bedding systems to be compared. Supplementary observations made by the dairy consultants and farmers were also recorded to provide a full assessment of the suitability of plasterboard paper as a bedding material. The development of the trial methodology was detailed in Section 3. The final methodology used is as detailed below. 5.1 Trial farms The trials took place at two dairy farms, A and B, near Barnsley in south Yorkshire. Both house their cattle during the winter using cubicles with concrete bases and conventionally use cereal straw as the bedding material. Farm A undertook the trial in a 100-cubicle building housing 95 cows. Farm B undertook the trial in a 60-cubicle building housing 52 cows. 5.2 Pre-trial investigations 5.2.1 Sampling and assessment of the cows and farms Before the bedding trial started, a number of assessments were made on each farm to provide baselines:

The cow cleanliness was scored according to the University of Wisconsin (UW) system. The results are given

in Appendices C and D for farms A and B respectively.

Teat condition was scored according to the TCI system, which included hyperkeratosis, skin texture and

roughness. The results are results given in Appendices E and F for farms A and B respectively.

The surface cleanliness of the housing system was assessed.

The general behaviour of the cows was also observed. 5.2.2 Sampling and assessment of the bedding material On the day the paper material was delivered to Farm A, samples of the fresh product were taken as detailed in Table 15.

Table 15 Sampling of bedding material

Parameter Type of sample Sample reference to: Results

Heavy metal content

500 g sample in stomacher bags Direct Labs TOXMO3 + DM Table 22

Mineral content 500 g sample in stomacher bags Direct Labs MINSO Table 22 Microbial contamination

500 g aseptically sampled using an inverted sterile bag; sample kept chilled and sent with ice packs for next day delivery to the laboratory

Direct Labs BOARD2 Table 16

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Table 16 Average microbial contamination of the bedding

Type of micro-organism Plasterboard paper (cfu/ml)

Straw (cfu/ml)

E Coli 10* 600 Psedomonas aeruginosa 10* 100* Staph aureus 710 100* Strep agalact 10 100* Strep dysgalact 10* 100* Strep uberis 90 100* Coliforms 880 Aerobic colony count 95000 * Below limit of measurement 5.3 Risk assessment As explained in Section 3, the initial trial design and methodology were amended so that the risk assessment would be undertaken on one of the trial farms immediately prior to the bedding trial. The risk assessment was undertaken on Farm A to ensure animal, operator and food safety prior to commencing the main trial. The cows had previously been living in the fields, with occasional indoor housing bedded on cereal straw. Table 17 gives the protocol used by the dairy consultants for the risk assessment. Within the two-week period of the risk assessment the farmer continued with his usual mucking out and re-bedding routine, but using the paper material. Bulk milk samples were taken by the milk buyer on a weekly random basis to test the milk for antibiotic contamination, extraneous water, butterfat content, protein content, urea content, SCC and Bactoscan. The results are given in Appendices C–J.

Table 17 Risk assessment protocol Day R0 Farm visit to conduct the pre-trial assessments to provide baselines:

teat condition, cow cleanliness and housing cleanliness; and sample of bulk milk taken for heavy metal analysis – 100 ml of fresh milk; sample reference

to Direct Labs TOXFD3 + Ca + SO4 on milk.

Day R1 Visit to advise the farmer on the use of the paper material. Cubicles mucked-out, removing the straw bedding, and bedded up with the paper material. Observations made on cow behaviour on introduction to the bedding.

Day R2 Visit to check on cow reaction and cleanliness. Adjust bedding advice as appropriate.

Day R4/5 Telephone contact to check on cow reaction and cleanliness. Adjust bedding advice as appropriate.

Day R7 Visit to: assess teat condition, cow cleanliness and housing cleanliness; take milk samples for heavy metal analysis; make general observations; and adjust bedding advice as appropriate.

Day R14 Visit to:

assess teat condition, cow cleanliness and housing cleanliness; take milk samples for heavy metal analysis; and make general observations.

Cubicles mucked out, removing the paper bedding, and bedded up with conventional straw.

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Cows behaved normally after an initial reluctance at the change in bedding. The bedding environment produced by the bedding was dry and there was no ingestion of material. There was only one bulk milk test during the two-week risk assessment period, but this showed normal levels for both SCC and Bactoscan; the SCC was slightly higher and the Bactoscan slightly lower than the previous test. The mineral analysis of milk showed very little variation from the control other than an elevation of the copper level. The plasterboard paper bedding passed the basic evaluation for animal welfare, milk hygiene and food safety. The full bedding trials could therefore begin after a two-week rest period with the Farm A cows being bedded on straw. 5.4 Bedding trial protocol and timescale Table 18 gives the protocol used by the dairy consultants for the bedding trial. Within the two-week period, the farmer continued with his usual mucking out and re-bedding routine, but using the paper material. Bulk milk samples were taken by the milk buyer on a weekly random basis to test the milk for antibiotic contamination, extraneous water, butterfat content, protein content, urea content, SCC and Bactoscan. Both farms began the full trial at the same time with Farm B having a pre-trial assessment carried out just before beginning to use the plasterboard paper material. In addition, the data from the risk assessment on Farm A could be used as part of the full trial as its protocol was identical to that of the trial. The trial methodology was a cross-over design whereby the cows at each farm were bedded on straw for two weeks and then the plasterboard paper for two weeks (Figure 12), with this alternation repeated a number of times.

Figure 12 Cow on plasterboard paper bedding at Farm B

Unfortunately Farm A experienced a cow health breakdown during the second period on straw and so the trial on Farm A was ended after two test periods. The cause of the health breakdown was a low-level combination of

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leptospirosis and bovine virus diarrhoea (BVD), and was not associated with the use of plasterboard paper as bedding. Due to time constraints on the project, the trial was modified to increase the final period on plasterboard paper at Farm B to four weeks. This actually had the additional benefit of allowing better assessments to be made of the longer-term use of plasterboard paper. The final trial timescale was as shown in Figure 13.

Table 18 Bedding trial protocol Day T0 Farm visit to conduct the initial assessments of the cows bedded on straw:

teat condition, cow cleanliness and housing cleanliness; sample of bulk milk taken for heavy metal analysis – 100 ml of fresh milk; sample reference

to Direct Labs TOXFD3 + Ca + SO4 on milk.

Day T1 Visit to advise the farmer on the use of the paper material and assist with the changeover to the bedding. Cubicles mucked out, removing the straw bedding, and bedded up with the paper material. Observations made on cow behaviour on introduction to the bedding.

Day T2 Visit to check on cow reaction and cleanliness. Adjust bedding advice as appropriate.

Day T4/5 Telephone contact to check on cow reaction and cleanliness. Adjust bedding advice as appropriate.

Day T7 Visit to: assess teat condition, cow cleanliness and housing cleanliness; take milk samples for heavy metal analysis; make general observations; and adjust bedding advice as appropriate.

Day T14 Visit to:

assess teat condition, cow cleanliness and housing cleanliness; take milk samples for heavy metal analysis; and make general observations.

Cubicles mucked out, removing the paper bedding, and bedded up with conventional straw.

Figure 13 Trial timescale

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5.5 Material logistics and handling 5.5.1 Supply and storage On both farms, the normal handling method for cereal straw was in big bales (250–400 kg). Unfortunately, it was not possible to supply the plasterboard paper in this form and so was supplied loose. The plasterboard paper was transported from the refining process at the composting site in bulk using moving floor articulated trailers with a nominal capacity of 25 tonnes. Access at Farm A was limited so the loads were tipped and shovelled into an open-fronted Dutch Barn style store (Figure 14). There was some mud contamination from the double handling, which caused some heating in the stack. In addition, there was some rain ingress onto the top of the heap which caused some additional heating. The heating appeared to be due to chemical reaction with water rather than decomposition as can be observed with cereal straw.

Figure 14 Paper bedding storage at Farm A

The bulk transporters were too large to access Farm B, so material was stored on Farm A and shipped to Farm B in a covered trailer (Figure 15). A total of 22.5 tonnes in five 4.5-tonne trailer loads of plasterboard paper were used by Farm B during the six weeks of bedding. Farm B was able to store the bedding in a clean, covered environment.

Figure 15 Loading a trailer for transporting the paper to Farm B

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5.5.2 Making the bed at Farm A Farm A used a tractor-powered tub chopper (Figure 16) for cereal straw which could blow bedding to both sides. The following were found:

To aid the spreading, the tub chopper needed to be adapted by removing most of the knives and spreading to

one side only. This was because the paper did not have the crisp physical nature of straw.

The machine could not be run in reverse due to the paper balling up. This increased the travelling time

through the building.

A front loader was used to put the material into the tub chopper, but there was a risk of bricks and stones

being accidentally scooped up and included in the bedding. This problem could be overcome in future by

storing the material on a firm surface or by providing it in baled form.

The weight of paper that could be loaded into the tub chopper was less than could be achieved with baled

straw.

Figure 16 Tub chopper used at Farm A

Despite these problems, the method was considered by Farm A to have worked well and the overall time to undertake the bedding operation similar to that using baled straw. Cubicles were bedded-up three times per week (Mondays, Wednesdays and Fridays) with sufficient bedding to cover the full week; 339 kg was used per day for 100 cubicles (3.4 kg/cubicle/day), which required two loads in the tub chopper. 5.5.3 Making the bed at Farm B Farm B initially tried to use a hydraulic-powered auger bucket, but the material compressed instead of flowing. Instead a system using a conventional loader bucket was devised where a half a bucket was placed between every five cubicles. The material was then spread into the cubicles by hand to produce an acceptable bed (Figure 17). Cubicles were bedded up three times per week (Mondays, Wednesdays and Fridays) with sufficient bedding to cover the full week; 476 kg was used per day for 60 cubicles (7.9 kg/cubicle/day). Farms using bulk material such as sawdust tend to use a conveyor bucket system to bed the cubicles. This may be an appropriate method for using plasterboard paper supplied loose.

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Figure 17 Freshly bedded cubicles at Farm B

5.5.4 Moisture control On both farms, normal practice with cereal straw was to use hydrated lime as an additional desiccant treatment to help absorb moisture in the bed. Both farms reported that the gypsum dust present on the paper was as effective in absorbing moisture and so they did not need to add any hydrated lime to the bed. The cubicle beds were hand-scrapped each milking (twice a day) to remove wet and soiled material and fresh bedding was pulled back from the front of the cubicle on the days in-between bedding up. 5.6 Compliance with health and safety requirements Plasterboard material is non-hazardous, although handling can give rise to localised dust and an unpleasant working environment. Gypsum dust is inert, although hygroscopic which means that it readily absorbs moisture from the atmosphere. A standard dust mask (EN 149:2001 FFP2) was used as personal protective equipment by the farmers when bedding up the cubicles. One operator with a pre-existing asthmatic condition commented that the dust was a problem but that it was no worse than using cereal straw through a tractor-powered straw chopper. It was observed that the dust cleared and settled faster with plasterboard paper bedding than with straw. 5.7 Compliance with environmental legislation The use of plasterboard paper on both farm sites was licensed by the Environment Agency as an exempt activity under Schedule 3, paragraph 15 (The beneficial use of waste) of the Waste Licensing Regulations (as amended). 5.8 Manure management It was envisaged that the expected proportion of 3kg plasterboard paper bedding to 30kg excrement and urine would fully render the plasterboard paper into the slurry. Both farms follow the guidelines as laid down in the Code of Good Agricultural Practice for the Protection of Water (the Water Code) for the handling, storage and use of manures and slurries. Before the trials began, the local Environment Agency office was notified about the proposed activities of the trials. Officials did not demand any additional requirements for the management of the resulting manure or slurry.

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5.9 Results of the bedding trial 5.9.1 Animal condition Leg and flank cleanliness The full cleanliness scores are given in Appendices C and D for Farms A and B respectively. The overall cleanliness scores for the cows at Farms A and B are shown in Figures 18 and 19 respectively as the percentage of the herd achieving a score of 1 or 2 on the UW scoring system. At Farm A the cows were in the process of beginning their winter housing period so had to contend with damp muddy field conditions at the start of the pre-trial period. Increasing cleanliness was observed during the total trial period on both treatment and control. The data show no difference between the plasterboard paper treatment and the straw control. The overall view was that plasterboard paper was a suitable replacement for straw and helped towards the improving cleanliness of the herd.

Figure 18 Cleanliness scores, Farm A

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Figure 19 Cleanliness scores, Farm B

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11-Dec 18-Dec 25-Dec 01-Jan 08-Jan 15-Jan 22-Jan 29-Jan 05-Feb 12-Feb

Perc

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Note The shaded areas indicate the periods during which the plasterboard paper was on trial

Figure 20 Clean dry feet at Farm B during bedding on paper

Teat condition The full teat condition scores are given in Appendices E and F for Farms A and B respectively, and are summarised in Tables 19 and 20. For Farm A, the data show the same pattern to the cleanliness scores of a steadily improving position as the winter housing period progressed. There was no difference between the paper and the straw bedding.

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Table 19 Teat condition scores, Farm A

Date Udder

cleanliness average

Cows exceeding limit (%)

Teat skin

Cows exceeding limit (%)

Hyperkeratosis Cows

exceeding limit (%)

23 October 2.7 63 1 2 1 0 15 November 2.4 47 1 2 1 2 20 November 2.3 35 1 1 1 1 27 November 2.2 24 1 3 1 1 1 December 2.1 18 1 3 1 1 15 December 2 8 1 3 1 1 22 December 2 7 1 8 1 3

For Farm B, the data show the same pattern to the cleanliness scores but with a slight improvement in hyperkeratosis scores as the period progressed. Overall there was no difference between the paper and the straw bedding. Figure 21 shows clean udders at Farm B during bedding on paper.

Table 20 Teat condition scores, Farm B

Date Udder

cleanliness average

Cows exceeding limit (%)

Teat skin

Cows exceeding limit (%)

Hyperkeratosis Cows

exceeding limit (%)

11 December 1.4 2 1 0 1.5 15 15 December 1.4 2 1 0 1.5 15 22 December 1.4 0 1 0 1.4 14 10 January 1.3 0 1 0 1.3 9 19 January 1.3 0 1 0 1.2 0 24 January 1.4 0 1 0 1.2 0

Figure 21 Clean udders at Farm B during bedding on paper

5.9.2 Milk quality SCC and Bactoscan Bulk milk samples were taken at both farms by the milk buyer on a weekly random basis to test the milk for antibiotic contamination, extraneous water, butterfat content, protein content, urea content, SCC and Bactoscan. At both farms the levels recorded during the trial were within the normal range for premium quality milk.

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The full results for SCC and Bactoscan are given in Appendices G and H for Farms A and B respectively, and are summarised in Figures 22 and 23.

Figure 22 Bulk SCC and Bactoscan scores, Farm A

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Note The shaded areas indicate the periods during which the plasterboard paper was on trial At Farm A the data show volatility of results during the transition from late autumn grazing to winter housing. This is normal occurrence. The results for the paper bedding periods are in line with the results for the straw bedding periods; although they appear to show a small reduction in Bactoscan and a small rise in SCC, neither is significant. The overall impression is that paper bedding performed at a reasonable level and was as effective as straw.

Figure 23 Bulk SCC and Bactoscan scores, Farm B

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Recycled plasterboard paper as animal bedding 42

Note The shaded areas indicate the periods during which the plasterboard paper was on trial At Farm B, there was a rise in both SCC and Bactoscan during the first period paper bedding but low levels were maintained in the second period. Generally there appears to be a small reduction in Bactoscan and a small rise in SCC, although neither is significant. The overall impression is that plasterboard paper performed at a comparable level to straw. Combining the SCC and Bactoscan data from both farms shows the overall effectiveness of the plasterboard paper bedding compared with the straw bedding control. Combined SCC data are shown in Figure 24 and combined Bactoscan data in Figure 25.

Figure 24 Combined SCC data from the two farms

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The SCC results for paper and straw are fairly consistent with two outlying scores for paper. The overall impression is that, while there was more variation with plasterboard paper, this was not statistically significant and the scores remained mostly below the target level of 200,000. As with the SCC scores, the Bactoscan results are fairly consistent for both paper and straw. There are four outlying scores, for straw. The overall impression is that plasterboard paper was as effective as straw at promoting low Bactoscan scores and udder cleanliness.

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Figure 25 Combined Bactoscan data from the two farms

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Microbial content of milk The results of microbial analysis for each milk sample are given in Appendices I and J respectively, and are summarised in Table 21 as the average of all samples from both farms.

Table 21 Microbial content of milk (cfu/ml)

Bedding material Type of micro-organism

Paper Straw

Average Range Average Range

E. coli @ 44 oC 7 1–16 5001 1–15,000

Enterobacteriaceae @ 37 oC 20 1–30 30,004 1–150,000

Moulds @ 25 oC 503 2–1500 2 1–6

Aerobic colony count @ 30 oC 1953 120–5000 1,005,900 1200 to 3 × 106

Yeasts @ 25 oC 1068 2–2300 1838 2–8500

The analysis showed considerable variation between samples, although the paper results showed a greater consistency than those from straw. The paper results appeared to deteriorate as the trial progressed, with higher counts in February 2007 than November 2006 suggesting a storage quality affect. This could possibly be due to the plasterboard paper material getting progressively damp from the generally wet weather conditions during the winter. The straw would have been stored from harvest and does not show any particular pattern other than greater variation, although two results appear to have rogue values believed to be due to contamination of the samples. Overall the results with plasterboard paper bedding show no greater microbial presence in the milk than those from straw, and there is a suggestion of a better consistency of material. However, the results show that the paper needs to be stored and handled in a dry environment to prevent deterioration in quality – as do most bedding materials.

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5.9.3 Mineral and heavy metal content of bedding and milk Samples of bedding material were analysed for minerals, particularly heavy metals. The results are given in Table 22. The results show a higher level of heavy metals in the plasterboard paper than in the straw. The dry matter (DM) was similar in both materials but ash content was significantly higher in the plasterboard paper due to the gypsum content. As expected from common farm experience, straw showed very low levels of most minerals. Lead in the plasterboard paper was double the value in straw and showed significant variation between samples of plasterboard paper. Mercury levels in the paper were 20 times higher than straw. Copper and zinc were up to 10 times higher but are considered required trace elements essential for dairy cows. Chromium in the paper was four times higher than in the straw. There was no evidence of any ingestion of plasterboard paper by the cows. Overall the mineral levels are higher in plasterboard paper than straw but are well below the toxic ingestion thresholds stated in Section 3.1.

Table 22 Mineral analysis of bedding material

Samples of milk were analysed for minerals and heavy metals to see if there were any differences between plasterboard paper and the straw control. The full results are given in Appendices K and L, and are summarised in Table 23. The only minerals to show any variance are copper and sulphate, which may be due to gypsum particles adhering to the teat surface being removed in milking. The heavy metals of most concern – lead, cadmium, arsenic and mercury – were no different between the materials. Overall milk mineral content was unaffected by the cows being bedded on the paper material.

Bedding material Parameter Unit

Paper Straw

Maximum tolerable limit in diet**

Oven DM % m/m 88.6 88.2 Total ash g/100 g DM 32.4 4.9† Lead mg/kg 100% DM 11.5 5* 30 Nickel mg/kg 100% DM 2.6 2* Zinc mg/kg 100% DM 32.6 4.8 Cadmium mg/kg 100% DM 0.1* 0.1* 0.5 Mercury mg/kg 100% DM 0.2 0.01* 2 Chromium mg/kg 100% DM 3.8 1.0* Copper mg/kg 100% DM 19.0 2.2 115 Calcium mg/kg 100% DM 7.1 Sodium mg/kg 100% DM 0.1 Potassium mg/kg 100% DM 0.1 Magnesium mg/kg 100% DM 0.1 Phosphorous mg/kg 100% DM 0.0 Sulphur mg/kg 100% DM 4.3 * Determination below test sensitivity ** US values from Table 6 † Standard Value MDC Feed into Milk Project Feeds Database

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Recycled plasterboard paper as animal bedding 45

Table 23 Mineral analysis of milk

Bedding material Parameter Unit

Paper Straw

Lead mg/kg 0.01* 0.01* Nickel mg/kg 0.0* 0.0* Zinc mg/kg 4.07 3.82 Cadmium mg/kg 0.005* 0.005* Arsenic mg/kg 0.1* 0.1* Chromium mg/kg 0.07 0.05 Copper mg/kg 0.18 0.09 Mercury mg/kg 0.004* 0.004* Calcium mg/kg 1177 1152 Sulphate mg/kg SAR 900 616 Ash g/100g 0.7 0.7 * Determination below test sensitivity {bookmark}

5.9.4 Use of the material Observations by the dairy consultants and feedback from the farmers were used to assess the use of the plasterboard paper bedding at the two farms according to the aspects identified in Section 3.1.3. The overall time spent bedding up with the plasterboard paper was little different than the time taken to bed with straw. The only difficulty experienced was on changeover days when, for the purposes of the trial, all bedding had to be removed from each cubicle by hand before bedding up with the fresh material. Bedding frequency with the paper was the same as with straw. Several methods were tested to apply the bedding including a horizontal tub chopper, a side-auger bucket, a small bale chopper and a conventional loader bucket. The auger and small bale chopper proved incapable of spreading the material while the tub chopper could only spread to one side at a time. The bucket method was effective but required direct spreading by workers – though it produced less dust than the mechanical methods. Some plastic bottles and ties that had evaded separation in the processing stage were detected by the farmers and removed by hand during bedding up. Usage levels of plasterboard paper were similar to those for straw bedding, although with Farm B in general using large quantities of bedding materials. Farm A used 3.4 kg/cubicle/day and Farm B used 7.9 kg/cubicle/day. The farmer survey carried out at the beginning of the project (Section 2) reported an average of 2.7 kg of straw/cow/day. At first, the cows were suspicious of the new material, which had a different smell and colour to straw. But the desire to rest soon overcame any resistance and cows laid up well. After that, cow usage of the paper was no different than with straw. The operators were generally happy with the plasterboard paper as a bedding material, with the main complaint being the changeover between materials. The plasterboard paper was easy to use and produced a good bed. Underfoot conditions were good, with Farm B also using the material to reduce foot slip when sorting out heifers in an adjacent yard. There was some evidence of gypsum setting hard behind a cubicle lip but there were no other similar observations. The gypsum content provided a dry bed environment which readily absorbed urine when trafficked into the passage, thus reducing the dampness under foot. Both farmers reported that they did not need to use hydrated lime with the paper bedding. This is a significant advantage as a major problem with use of lime is that it can lead to rashes on sensitive skin areas on the cow, such as the udders, which then require treatment.

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There was no detection of anaerobic breakdown of gypsum producing the characteristic hydrogen sulphide smell or any other adverse characteristics. Both farmers said that the decision on choice of future bedding would rest on the logistics and price of the plasterboard paper. A baled system, complementary to straw would be the most favoured handling system. An evaluation of the relative cost of the different bedding materials is given in Section 6. After the trial, Farm B also reported that a combination of plasterboard paper applied once per week with a top dressing of chopped straw gave the best bed of all – utilising the best features of both materials. 5.9.5 Manure handling The bedding routine was for excreta and soiled bedding to be removed from the cubicle bed into the passage on a daily basis. The passage was scraped at each milking (twice daily) to remove all excreta, urine and soiled bedding from the building. As Figure 26 shows, there was a tendency for paper bedding in the passageway to become slurry.

Figure 26 Cows bedded on paper at Farm A. The paper bedding is trafficked into the passageway by cow movement, where it mixes with excrement to produce slurry.

The quantity of bedding used at Farm A (3.4 kg/cubicle/day) and at Farm B (7.9 kg/cubicle/day) suggests a mix of approximately 14.7 : 1 (excrement and urine : bedding) at Farm A and 6.3 : 1 at Farm B. As shown in Figure 28, the resulting slurry was such that the soiled bedding was well rendered into it.

Figure 27 Paper bedding slurry at Farm A

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Both farms were able to use the same slurry management system for the paper bedding slurry as they normally used for straw bedding slurry. Early in the trial period (November 2006), the slurry at both farms was spread on maize stubble (Figure 28) and grassland (Figure 29). A lower application rate was used on the grassland and very little paper was visible on top of the grass (Figure 29). Later in the trial as the land became saturated with rain, the slurry was stored for spreading in the spring. To enable its storage in a field heap the slurry at Farm B was mixed with straw-based bedding from other yards and had a lower water content.

Figure 28 Paper bedding slurry spread on maize stubble

Figure 29 Paper bedding slurry spread on grassland

Important note The Environment Agency is currently ruling on whether manure and slurry containing plasterboard paper bedding is defined as a waste or not in England and Wales. This could have implications for the licensing procedure for spreading the manure or slurry to land. Until a decision is announced, any farmer considering using this bedding material is recommended to consult their Waste Regulator’s local office.

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6.0 Economic evaluation The challenge for plasterboard bedding was to be as effective as other materials as a bedding, to be safe to use from a cow and human health perspective, and be competitive on price compared with the main bedding materials in current use. The farmer attitude survey conducted at the start of the project (Section 2) found that price was a modest consideration, scoring less than the ability to provide for the needs of the cow. This section draws information from the farmer survey and the results of the bedding trial (Section 5) to evaluate the economic competitiveness of plasterboard paper in comparison with other materials as bedding for dairy cows in the UK. A cost analysis of the material processing stage of the project is given in Section 4.9. Many of the costs were unique to the trial and would not occur under operational conditions if the process was carried out by at a plasterboard recycling facility rather than a separate site. Throughput is a key factor in reducing processing costs and could be increased if the plasterboard paper had a lower gypsum content as a result of more effective separation during the primary plasterboard recycling process. The need and costs for processing to remove contaminants could even be avoided altogether if they were removed before the waste plasterboard was recycled. 6.1 Bedding material usage Table 24 shows the rate of bedding usage by the two farms in the trial per cubicle per day, and the corresponding amounts if this rate were used over an entire winter period of 180 days. The average rate of straw use at the two farms was in line with the average from the survey findings of 2.7 kg/cow/day (Section 2), although individually Farm A had a lower use of bedding and Farm B had a much higher use. Plasterboard paper was used at twice the rate of straw; the average rate was 5.7 kg/cubicle/day. The use of higher levels of plasterboard paper may have been the result of using a ‘novel’ material and therefore more was used than was strictly necessary. It is also possible that a higher rate was used because the material was provided free. Overall the efficacy results (Section 5.9) suggest the correct amount was used to achieve the bedding objectives of a clean dry bed.

Table 24 Trial bedding usage

Farm A Farm B Survey

Straw Paper Straw Paper Straw Sawdust Sand Paper

Number of cows 95 95 52 52

Number of cubicles 100 100 60 60

Occupancy rate 95% 95% 87% 87% 94%* 94%* 94%*

kg/cubicle/day 1.6 3.4 4.2 7.9 - - - 5.7

kg/cubicle/week 11 24 29 56 - - -

kg/cubicle/winter** 289 610 750 1428 - - -

kg/cow/day - - - - 2.7 1.4 8.6 6.0

kg/cow/week - - - - 19 10 60 42

kg/cow/winter - - - - 486 252 1548 1084

Tonnes/100 cubicles/winter

29 61 75 143 46 24 146 102

* Average occupancy rate from the bedding survey ** Standard winter housing period of 180 days The key to farmer uptake of plasterboard paper bedding will be its cost compared with straw or other bedding materials. The main bedding materials (92%) used in cubicles in the farmer attitude survey were straw, sawdust and sand. Average usage rates for these materials are shown in Table 24, as the use per cow. To enable comparison with the usage rates in the bedding trial, the survey rates have been standardised to use per 100 cubicles per 180 day winter period by using the average occupancy rate from the survey of 94%.

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6.2 Other cost considerations The economic comparison of the bedding materials is given in Section 3.3. Outlined below are other factors which needed to be considered as they could affect the comparison. Bedding time with the plasterboard paper and the straw was similar on both farms although different methods were used to bed up the cubicles with the paper (Section 5.5). Although the hand shovelling of paper at Farm B was slower than the bale chopper used at Farm A, the additional time on three days each week was offset by the reduced daily cleaning chore. The need for a dry bedding material necessitates dry storage conditions for all types of bedding. Cereal straw will denature and eventually compost when wet, whereas plasterboard paper begins to heat up due to the chemical reaction between gypsum and water. The storage requirements are therefore the same for both bedding materials, although some farmers leave straw uncovered for the early part of the winter. For the bedding trial the plasterboard paper was transported and used in bulk; a baling option was considered but could not be tried due to time and cost constraints. Straw is generally handled in large bales (250–400 kg) and sawdust is mostly supplied in bulk, although some is used as small 25-kg bales. As a bulk material, plasterboard paper suffered from low density (as would straw). Presenting the material in a large bale format would be advantageous. There were no additional costs when using the plasterboard paper compared with straw in order to meet health and safety requirements. Any additional costs to meet environmental legislation will depend on the view taken by the Waste Regulators as to whether manure or slurry containing plasterboard paper bedding is classed as a waste or not. Farmers are advised to consult their Waste Regulator’s local office. In the trial the same slurry management system could be used for the paper bedding as for the straw bedding and there were no additional costs. Therefore no additional costs are included in the economic comparison. 6.3 Economic comparison of plasterboard paper and other bedding materials From the farmer survey average costs for the top three conventional bedding materials were determined (Table 25). On the two trial farms, the straw cost was quoted as £30/tonne. This slightly lower price than the average found in the survey may reflect geographical differences between the trial sites in Yorkshire and the normal western location of the dairy industry. Table 25 shows the calculated equivalent price for plasterboard paper to be cost neutral with the conventional bedding materials. Similar prices are shown for the farms in the bedding trial for comparison, based on the material costs and quantity used. For the materials from the survey, plasterboard paper at a usage rate of 5.7kg/cubicle/day was used (Table 24).

Table 25 Cost comparison, bedding material only

Farm A Farm B Survey

Straw Straw Straw Sawdust Sand

£/tonne 30 30 39 48 15 pence/cow/day - - 10.5 6.7 12.5 pence/cubicle/day 4.8 12.5 9.9 6.3 11.7 Total, £/100 cubicles/week 34 88 69 44 82 Total, £/100 cubicles/winter 868 2250 1782 1137 2110 Equivalent plasterboard paper cost, £/tonne 14.22 15.76 18.33 11.70 21.71

Farmers routinely use hydrated lime as an additional desiccant with conventional bedding materials, whereas the bedding trial demonstrated that plasterboard paper has the advantage that no further desiccant is required. This

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saves both money and time. Table 26 shows that although the cost per day for lime is small it does increase the price plasterboard paper bedding can be yet remaining cost neutral with the conventional bedding materials.

Table 26 Cost comparison, bedding material and hydrated lime

Farm A Farm B Survey

Straw Straw Straw Sawdust Sand

Bedding, pence/cubicle/day 4.8 12.5 9.9 6.3 11.7 Lime, pence/cubicle/day 0.4 0.4 0.4 0.4 0.4 Bedding+lime, pence/cubicle/day 5.2 12.9 10.3 6.7 12.1

Total, £/100 cubicles/week 37 90 72 47 85 Total, £/100 cubicles/winter 940 2322 1854 1209 2182 Equivalent plasterboard paper cost, £/tonne 15.40 16.26 19.07 12.44 22.45

From Table 26 it can be concluded that, potentially, plasterboard paper at a price of ~£18/tonne would be commercially competitive with straw and sand. To be competitive with sawdust it would need to be supplied at a lower price, of ~£12/tonne. 6.4 Transport costs The above prices would be for the bedding material as delivered to the farm, and so would need to include the transport costs. Table 10 stated that transport costs for the 25-tonne bulk loads of plasterboard paper were approximately £8/tonne + 8 pence/tonne/mile. This suggests supply of plasterboard paper material at £18/tonne would limit the delivery radius to less than 125 miles from the plasterboard recycler. However, this should be only taken as indicative. It is possible that delivery costs could be reduced if the bedding material were in a different format (such as baled), or if the recycler/supplier established long-term contracts with a haulage contractor. 6.5 Estimate of market value Section 2 suggested that out of a total purchased bedding market of 1.1 million tonnes per year, cubicle housing makes a market of around 780,000 tonnes per year. Table 27 shows that the total value of the purchased bedding market for cubicle housing is £26 million per year. Just a 5% penetration into this market by plasterboard paper could potentially be worth ~£1.3 million per year. Based on the cost neutral equivalent prices for plasterboard paper, this market value could correspond to a market tonnage of around 87,000 tonnes.

Table 27 Estimated cubicle bedding market value

Survey

Straw Sawdust Sand Total

Purchased cubicle bedding market, tonnes 780,000

Percentage of users 40% 30% 22% 92%

Market share, tonnes 312,000 234,000 171,700 717,700

Bedding cost, £/tonne 39 48 15

Market value, £/year 12,168,000 11,232,000 2,575,500 25,975,000

5% market value, £/year 608,400 561,600 128,800 1,300,000

Equivalent plasterboard paper tonnage 33,500 47,350 6,000 86,850

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Should future trials prove that plasterboard paper is also suitable for use in loose-yard housing, then the potential total market at 5% penetration could be closer to £2 million per year.

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7.0 Conclusions This project examined the feasibility of using plasterboard-facing paper obtained from waste plasterboard recycling as a bedding material for dairy cows in winter housing. 7.1 Farm attitude survey This project began with a survey of farmers’ attitudes to the use of the bedding materials for dairy cows. The survey confirmed usage of animal bedding at around 2.7 kg/cow/day in cubicles and 12 kg/cow/day in loose yards, giving a total winter usage in the UK of approximately 1.6 million tonnes. The proportion of cows in cubicles was slightly lower than expected at 79%, but the occurrence of purchased bedding was higher at 85%. The overall size of the purchased bedding market in the UK is estimated at approximately 1.1 million tonnes. Loose yard farms tend to use mostly home-produced straw and are more price sensitive, with a narrower price range. Cubicle system farms use a more diverse range of materials, have a wider range in prices, and are more likely to consider other materials. The daily cost of bedding material is approximately three times higher for loose yarded cows than for cubicle-housed cows. The common important requirements are for bedding material to be comfortable, dry, absorbent, easy to handle, and to keep cows clean. Handling is an important consideration, as any new material must fit the existing system. If plasterboard waste is to challenge straw in loose yards, then a big bale format will be required. For cubicles, it is important that the material fits in with the existing slurry system so that storage and disposal via pumped systems to land can be carried out efficiently. Loose yards are more tolerant in this respect due to the rudimentary methods used to clean and remove solid manure to field stacks for composting. The survey found that price is less of an issue than functionality, suggesting that cost should not be a barrier to the uptake of plasterboard waste as animal bedding provided:

there were no risks to human and animal health from its use; and

it could meet the key characteristics of a bedding material demanded by farmers.

7.2 Development of the trial The next step was to demonstrate the practical viability of the plasterboard waste in a bedding trial. The following parameters were used as the basis of the assessment of its viability as a bedding material:

animal condition – cleanliness and teat condition;

milk quality – somatic cell count (SCC), Bactoscan, microbial content, and mineral/heavy metal content;

use of the material; and

manure and slurry handling.

An important element of the project was a risk assessment to be undertaken before the bedding trial itself to ensure there would be no risks to the cows, those taking part in the trial and the consumers of the milk produced during the trial. A farm chosen for the risk assessment proved, on a site visit, to be unsuitable and the trial design was modified to incorporate the risk assessment immediately before the trial began at one of the two participating farms. No problems or unacceptable risks were encountered during the risk assessment and the trial went ahead as planned. A further revision to the initial trial design was required to incorporate a processing stage to remove unacceptable levels of contamination observed in a sample of reclaimed plasterboard paper provided by a plasterboard recycler. To accommodate the unforeseen costs of this additional stage, trials were limited to those farms using cubicle housing. 7.3 Material processing Mechanical separation was made difficult by the variation in size, density and material of the contaminants present in the plasterboard paper waste. The level of contamination was relatively low but sufficient to render the material unsuitable for direct use as a bedding material. A mobile separation unit supplied by REDOX Recycling Technology successfully removed the small pieces of gypsum, aggregates, screws, nails, dense metal items, wood and heavy plastics present in the material supplied by a plasterboard recycler. However, the mostly plasterboard paper stream contained low density items such as

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squashed drinks cans, drinks bottles, pieces of tape measure, plastic banding and sack ties. These remaining contaminants had a similar size and density to the paper stream and had to be removed by hand. The gypsum content was reduced by the processing, but this was mainly loose granules of gypsum; gypsum powder still remained on the paper. The heavy metal content was increased by the processing but remained within acceptable levels. The cost of separation in the trial was high (£186/tonne) due to the low throughput (4 tonnes/hour) and low yield (58%). Once the unique costs of the trial were removed, actual processing costs were £65/tonne. This cost could be reduced if:

yield could be improved to the target of 80% by reducing the gypsum content or small contaminants at the

recycling stage; and

throughput could be doubled by reducing the overall level of contamination.

Processing costs could be removed altogether if an acceptable bedding material was produced directly from the waste plasterboard recycling process. This may be achieved if more of the contaminants were removed at source on the building site by ensuring correct waste segregation as, once wastes are mixed together, sorting becomes more difficult. Shredding the contaminants in with the plasterboard waste before separation makes the problem worse. Separating out the contaminants before shredding may also benefit the plasterboard recycler by reducing wear on the recycling equipment The low density of the paper material meant that it had to be transported in bulk in moving floor trailers. This cost around £8/tonne plus 8 pence/tonne/mile, giving a competitive cost of £16/tonne for a 100-mile journey and £24/tonne for one of 200 miles. 7.4 Bedding trial During the trials at the two participating farms, plasterboard paper performed as well as straw as a bedding material for dairy cows. Its effectiveness as a clean bedding was confirmed in both animal cleanliness and teat condition scores. There was no significant difference in the results from either bedding material. Microbial analysis of milk showed significant variation in the samples from cows bedded on straw whereas those from cows bedded on plasterboard paper were more consistent. On average, plasterboard paper had slightly lower levels of microbes than straw. There was a suggestion that the somatic cell count (SCC) could be slightly raised and Bactoscan scores lowered in milk from cows on plasterboard paper bedding compared with straw. The mineral analysis of bedding materials confirmed that plasterboard paper had higher levels of most metals compared with the relatively inert straw, but the levels were well below those considered the maximum safe levels should the cows eat the bedding. There was no evidence that cows did ingested the material – unlike straw, which they consumed readily. The mineral analysis of milk showed no difference in most parameters except copper and sulphate, which were three and 1.5 times respectively higher in samples taken while the cows were on paper bedding than on straw. However these increased levels were not of concern and the milk continued to be bought by the milk buyer. The plasterboard paper was supplied to the farms loose in bulk. Large bales would offer logistical advantages both for haulage and for ease of use by farmers. It requires the same dry storage conditions as straw to avoid degradation. It can be applied to the cubicles by hand or using a tub bale chopper with reduced blades; auger buckets are not suitable for bedding up. The rate of use of plasterboard paper as an animal bedding is effectively double that of straw and four times that of sawdust in terms of weight. After initial wariness of the different material, the cows laid up well during the trials and then no subsequent wariness was noticed.

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A significant benefit of the paper bedding being derived from plasterboard was that gypsum powder on the paper increased its ability to absorb water, which meant that it was not necessary for the farmers to add a desiccant such as hydrated lime to the bedding. This reduced time in cleaning the beds, and money. The material fully rendered into the slurry and the farmer’s usual slurry management system could be used. Both farm sites were licensed by the Environment Agency as an exempt activity under Schedule 3, paragraph 15 (The beneficial use of waste) of the Waste Licensing Regulations (as amended) and the local Environment Agency did not have any additional requirements for managing the slurry. Any farmers considering using this material should contact their Waste Regulator’s local office beforehand to gain the necessary waste exemption. 7.5 Economic evaluation The equivalent value of the plasterboard paper compared with straw was about half that of straw. The two farms participating in the trial paid £30/tonne for straw, giving an equivalent plasterboard paper value of ~£16/tonne. Compared with the average straw price found in the survey of farmers’ attitudes to bedding, the equivalent price becomes ~£18/tonne. This is comparable for sand, but against sawdust, the equivalent price is lower at ~£11/tonne. Overall use averaged ~1 tonne/cubicle over a 180-day winter housing period. 7.6 Overall Plasterboard paper satisfies the key requirements demanded by farmers to provide clean, dry and comfortable bedding for their cows. It was as effective as straw as a bedding material for dairy cows in trials conducted on two farms in south Yorkshire. Overall farmer reaction was favourable; the trial hosts felt that the plasterboard paper worked well and would be attractive if the logistics and handling issues on farms could be addressed. Price, availability and quality will be the factors limiting uptake of plasterboard paper waste as a bedding material. Ensuring the supply is free from contaminants (including plastic and foil backing) and can be supplied in a logistically complementary way to existing handling systems is important. The total UK market for purchased bedding is around 1.1 million tonnes per year. Of this the amount used in cubicle housing is around 780,000 tonnes per year, with a value of £26 million. If plasterboard paper bedding can attain a 5% share of this market, it could be worth £1.3 million, by supplying around 87,000 tonnes per year.

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8.0 Recommendations 8.1 Producing the material Extensive processing of recovered plasterboard paper to make it fit for use as animal bedding is not cost effective. Aspects such as contaminant removal should instead occur either before or during the plasterboard recycling process. It is therefore envisaged that plasterboard recyclers would be producers of the bedding product, and they may need to consider the following. A. Contaminant removal

Encourage improved waste segregation at source (i.e. on construction and demolition sites) to minimise the

subsequent need for separation of contaminants.

Carry out a primary sort to remove clearly visible contaminants before commencing processing to separate

the gypsum and the paper. This may include:

o over-band and under-band magnets to remove nails/screws and other ferrous objects, and an eddy

current separator to remove non-ferrous metals;

o hand picking on a belt for large items, such as wood, plastic, cable etc.

Pass the processed material through further magnets and a separator to remove nails/screws released from

the waste plasterboard.

Undertake a visual quality check of the paper material.

B. Residual gypsum

Although some residual gypsum as powder on the paper is desirable particles larger than 5mm are not. The paper material may need to be passed through a final mechanical sort with either a windshifter or trommel to grade out larger gypsum and aggregate particles.

C. Transport

Efficient transport of the material can be achieved using moving floor trailers although access at farms may be an issue with such large vehicles. Developing baling so that bedding material can be delivered to farms in 250–400 kg bales, which would fit with existing baled bedding systems, would increase the material’s appeal.

D. Quality

A quality standard should be defined to enable producers to sell, and farmers to buy, a quality assured animal bedding product. This should be an agreed standard between the plasterboard recycling and dairy farming sectors.

8.2 Using the material A. Plasterboard paper is classed as a waste, so before using it a waste exemption application should be made to

the Environment Agency or the regulators in Scotland or Northern Ireland. They should also be consulted to determine any additional requirements on the manure or slurry produced from its use.

B. Plasterboard paper bedding material should be stored under cover, preferably in a building, away from

significant sources of moisture. C. Wearing a dust mask may be required during handling. D. Bedding-up cubicles has worked using a tub chopper with reduced blades, and by hand. Auger buckets do

not seem to work effectively. E. An application rate twice that of straw is effective. F. Additional desiccants to absorb moisture on the bed may not be required.

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8.3 Further development A. Clarification and guidance will be required from the Waste Regulators (Environment Agency in England and

Wales, SEPA in Scotland and EHSNI in Northern Ireland) on licensing requirements for the use of plasterboard paper as a bedding material.

B. Alternative spreading mechanisms for bedding-up the cubicles should be examined to give guidance on best practice to farmers.

C. The availability and use of plasterboard paper as a bedding for dairy cows should be promoted.

D. Additional studies with loose housed cows should be conducted to investigate the effectiveness of plasterboard paper as bedding.

E. Additional studies should be conducted on the effectiveness of the material as bedding for other large

animals, such as horses.

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9.0 Glossary Bactoscan A rapid screening test of the bacteriological content in milk samples.

Brisket board An addition to cubicles to position the cow correctly.

Cereal straw/rape straw Fibrous residue left after the harvest of cereals and oilseed rape.

Colony-forming units (cfu) A measure of viable bacterial numbers.

Cubicles Dairy cow housing divided into separate compartments by steel or wooden divisions so that the cows lie in organised rows.

Head rail An addition to cubicles to position the cow correctly.

Hyperkeratosis Excessive stimulation of the keratinous lining of the teat canal, often associated with teat skin dryness.

Loose yards Dairy cow housing without any separate divisions allowing cows to lie as they choose.

Mastitis Infection of the udder that causes discomfort to the cow and a loss milk output. Milk from infected cows cannot be sold.

Paper shreds Waste material produced from paper industry, usually de-inked to remove heavy metals.

Plasterboard waste In general this refers to segregated off-cuts of plasterboard from construction sites and production scrap from plasterboard manufacturing plants.

Sand Washed sand.

Sawdust Fine wood particles.

Shavings Larger wood particles.

Slurry Liquid animal manure with a low dry matter and little bedding present.

Somatic cell count (SCC) A measure of the number of leucocytes (white blood cells) contained within the milk. The white blood cells are generated by the immune system of the cow in response to a number of challenges including mastitis pathogens.

Windshifter Materials processing equipment which uses high pressure air jets to separate light and heavy materials by density.

Trommel Rotating cylindrical perforated drum to separate materials of different sizes.

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Appendix A Laboratory analysis of unprocessed plasterboard paper material

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Appendix B Laboratory analysis of processed bedding material

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Appendix C Cow cleanliness scores Farm A

23-Oct 15-Nov 20-Nov 27-Nov 01-Dec 15-Dec 22-Dec

Flanks 1 19 23 28 31 31 31 31 2 59 57 52 51 52 52 52 3 20 18 18 16 15 15 15 4 2 2 2 2 2 2 2

1+2 78 80 80 82 83 83 83 Legs

1 0 0 0 0 2 2 2 2 0 0 25 48 58 65 67 3 3 67 47 36 31 31 29 4 97 33 28 16 9 2 2

1+2 0 0 25 48 60 67 69 Farm B

11-Dec 15-Dec 22-Dec 10-Jan 17-Jan 24-Jan 05-Feb Flanks

1 65 - 71 69 64 66 67 2 31 - 26 30 35 33 32 3 4 - 3 1 1 1 1 4 - - - - - - -

1+2 96 97 99 99 99 99 Legs

1 75 - 75 75 75 75 75 2 25 - 25 25 25 25 25 3 - - - - - - - 4 - - - - - - -

1+2 100 100 100 100 100 100

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Appendix D SCC and Bactoscan results Farm A

Date SCC

(thousands per ml) Bactoscan

(thousands per ml) 03-Oct 84 19

12-Oct 96 75

15-Oct 98 63

22-Oct 88 38

30-Oct 181 59

04-Nov 106 23

12-Nov 71 27

20-Nov 154 13

28-Nov 114 27

06-Dec 107 26

13-Dec 81 23

18-Dec 168 30

26-Dec 156 18

04-Jan 144 43

12-Jan 147 25

18-Jan 164 36

23-Jan 134 18

28-Jan 247 25 Farm B

Date SCC

(thousands per ml) Bactoscan

(thousands per ml) 03-Nov 194 8

11-Nov 131 18

15-Nov 153 22

01-Dec 146 14

07-Dec 179 8

13-Dec 144 12

17-Dec 194 14

21-Dec 481 46

27-Dec 393 14

02-Jan 196 86

12-Jan 170 13

20-Jan 122 8

24-Jan 85 10

03-Feb 256 20

09-Feb 190 22

19-Feb 210 18

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Appendix E Bacterial analysis of milk

Date 27-Nov 2006 01-Dec 2006 11-Dec 2006 11-Dec 2006 27-Dec 2006 27-Dec 2006 09-Jan 2007 06-Feb 2007 06-Feb 2007

Farm A A A B A B A A B

Bedding Paper Straw Straw Straw Straw Paper Straw Straw Paper

E Coli 1 1 15,000 15,000 2 3 1 2 16

Enterobacteriacease 1 150,000 15,000 15,000 4 30 9 12 29

Moulds 6 1 6 3 1 2 1 1 1,500

Aerobic CC 120 30,000 3,000,000 3,000,000 1,200 740 2,600 1,600 5,000

Yeasts 2 210 2,300 8,500 12 2 2 3 3,200

Appendix F Mineral analysis of milk

Date 13-Nov 2006 27-Nov 2006 01-Dec 2006 11-Dec 2006 11-Dec 2006 15-Dec 2006 15-Dec 2006 10-Jan 2007

Farm A A A A B B B A

Bedding Straw Paper Straw Straw Straw Paper Paper Straw

Lead mg/kg 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Nickel mg/kg 0 0 0 0.1 0 0 0 0

Zinc mg/kg 3.63 4.33 3.41 3.92 3.98 3.79 4.08 3.66

Cadmium mg/kg 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005

Arsenic mg/kg 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Chromium mg/kg 0.03 0.07 0.06 0.03 0.03 0.08 0.06 0.06

Copper mg/kg 0.06 0.16 0.17 0.06 0.01 0.14 0.25 0.1

Mercury mg/kg 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004

Calcium mg/kg 1170 1150 1090 1290 1130 1110 1270 1080

Sulphate mg/kg SAR 723 717 429 684 606 964 1020 537

Ash g/100g 0.8 0.65 0.68 0.7 0.7 0.7

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Written by: Nick Holt-Martyn, The Dairy Group Ltd

The Dairy Group Ltd

Published by Waste & Resources The Old Academy Tel: 01295 819 900 Helpline freephone Action Programme 21 Horse Fair Fax: 01295 819 911 0808 100 2040 Banbury, Oxon E-mail: [email protected] OX16 0AH www.wrap.org.uk