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Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2010 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872

Digital Re-print - May | June 2011 Pellet production to save energy, improve feed efficiency and safety

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The use of pelleted feeds is now almost universal for meat producing animals or wherever biosecu-

rity is a paramount concern.

The efficiency of the pelleting process has a huge impact of feedmill profitability and throughput and with 90 percent of animal feed in Europe being pelleted every feedmill

should be monitoring pellet efficiency.

From a production point of view, pelleting feeds increases the bulk density of the ration,

allowing more tonnage to be delivered per truck. This saves on space and transport costs.

Pelleted feeds are easy to handle in bulk or in bags and save time at the mill and during delivery operations because they have enhanced flow properties that allow for good conveying by screw augers, as well as improved discharge behaviour from feed bins due to reduced bridging compared to mash.

Generally, it is only in layers where mash feeds are still used and this is primarily to prevent overconsumption of nutrients.

Pellets have other advantagesPelleted feed is for example nutritionally

consistent from pellet to pellet with each pellet containing the correct balance of amino acids, minerals and vitamins. Pelleted

feeds provide no opportunity for ingredient selection during consumption by fussy feed-ers and there is less wastage with pelleted feeds.

Pelleted feeds are also more digestible as a result of starch pre-gelatinisation and protein denaturation. And, it has also been reported in pigs that an additional benefit of pelleting is that a finer grist size can be used and this has also been found to increase digestibility.

Responses in weight gain and feed efficien-cy of birds fed pelleted diets is substantially improved when the pellet quality is good.

While it has been suggested that the improvement in performance is solely the result of increased diet digestibility due

Pellet production to save energy, improve

feed efficiency and safetyby Murray Hyden C Biol, Technical Director/Director of Biosecurity, Kiotechagil

Grain&feed millinG technoloGy14 | may - June 2011

FEATURE

to the heat treatment involved, research has shown that when pelleted diets are re-ground to the consistency of mash, the growth response to pelleting is eliminated.

As long ago as 1978, Proudfoot and Sefton reported that body weight and mon-etary returns were inversely related to the proportion of fines in finisher diets and the same is true today.

The benefits of pelleted feeding may be attributable to the fact that birds fed pelleted diets expend less energy to consume the same level of nutrients as those fed mash

feeds. Early observations showed that birds could consume their dietary requirements in four percent of the day when fed pellets compared with 15 percent of the day when fed mash feeds.

In pig production, the heat treatment during pelleting improves the digestibility of maize, which can result in a six-to-eight percent improvement in daily gain and feed conversion.

Secondary, benefits of pelleting are that the temperature and moisture improves digestibility and more recently this benefit

has been further enhanced by using the new thermally stable feed enzymes that are added to the feed before pelleting as opposed to the more traditional post pellet applications.

The Kiotechagil Feedzyme enzymes for example are inherently stable, without encapsulation, at temperatures up to 95°C in the conditioner before pelleting. This gives them a head-start on traditional enzymes.

However, probably the best know indi-rect benefit of pelleting is biosecurity. Most of the common pathogens such as salmo-nella, Escherichia and Campylobacter are

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FEATURE

improve the digestibility of the DDGS, a pellet binder is often required to achieve a suitable pellet quality from this high fibre ingredient.

A low inclusion binder, like Kiotechagil Mastercube, can really help overcome many of the problems associated with the feed formulation and can also help over-come some of the engineering shortfalls such as short conditioners or poor steam quality.

One other important factor of pellet binders is that they help maintain pellet qual-ity during seasonal changes in raw material quality. The pelletability of freshly harvested cereals is often quite different to the last of the previous harvest grains.

Simply adding water to the grist may exac-erbate problems at the pellet press and the use of a pellet binder can help overcome the problems.

The selection of a low inclusion binder has the advantage in that it minimises the impact of nutrient density so feed costs can be maintained. Mastercube, unlike some binders, is also a useful calcium source so it can easily be incorporated into the ration formulation programmes.

Remember that without a pellet binder fines can be a real problem and fines returns at the feedmill do not just mean expensive double pelleting for the returned material but also a reduced throughput at the mill.

Pellet breakage during transport and stor-age is also wasteful.

A pellet binder must do more than simply bind the grist at the die, it must also confer an increased pellet hardness to enable pel-lets to be blown, augured and transported without being crushed.

Mastercube is both a binder and a hard-ener and it uses only EU approved ingre-dients. The primary binder is a natural plant gum that is tested to comply with EU standards and the hardener is a high quality calcium sulphate, which is approved as a nutrient and has a dual function as a calcium source and a hardener.

A feedmill operating efficiently and dust free is a pleasant place to work. It is safe for the operators and easier to keep clean. Fines, settling as dust on floors and equipment, will soon pick up moisture and will become a habitat for enteropathogens.

The requirement therefore for pellet binders that do not compromise nutrient density is even more important today than it was just a few years ago. The modern breeds used in production have been heavily selected for maximizing feed intake and the response to pelleted diets is likely to be much more significant than was reported just twenty or thirty years ago.

Selecting the right pellet binder is cost effective in so many ways and can be a real benefit in terms of digestibility, biosecurity and mill throughput thus making a quality pellet binder pay for itself many times over.

Feed formulation plays a major part in final pellet quality and high protein cereals such as wheat will contribute more to pellet quality than maize, oats or barley.

Dietary fat is known to have an inverse relationship with pellet quality, hence the use of post pellet fat spraying for certain rations. When fat is incorporated into the feed the added fat coats starch granules and prevents water uptake, which in turn impairs the heat transfer necessary for gelatinisation.

When high levels of dietary fat are used or when maize is the primary cereal in the ration formulation, tradi-tional binders such as thixotropic bentonite clays or lignosulphonates (the waste product from the wood pulping process to manufacture paper) have been used to improve pellet quality.

However, neither of these bind-ers provides any substantial nutri-tional value to the diet.

In fact, both these ingredients are incorporated at high inclusion rates and actually dilute the nutri-ent content of the feed resulting in more expensive raw material usage to compensate.

Reduced fines and improved digestibility lead on to further improvements that are often overlooked. For example, improved feed conversion and nutrient utilisation reduces the volume of excreta which ben-efits the environment, so we have less feed being used to improve growth rates and improvements to the environment.

With cereal prices ever increasing in price the temptation to use more co-products, such as DDGS from bioethanol production, is much greater. However, DDGS inclusion can result in reduced pellet quality, which is because the main binding agent, starch, has been removed to produce ethanol. Whilst enzyme systems have been developed to

non-spore forming bacteria and are there-fore sensitive to heat. The temperature required is often not as high as expected with S. typhimurium being killed after just 10 seconds at 70°C but requiring seven minutes at 60°C.

None-the-less, pelleting is a very high energy process (and is becoming more so with energy prices increasing). The use of high quality pellet binders can reduce energy requirements in three ways.1 Poor pellet quality results in higher

fines levels and more returns, which is energetically inefficient

2 Pellet binders help lubricate the die which reduces energy requirements as well as increasing mill throughput. Lubricating dies minimises wear so they should last for 25,000–30,000 tonnes with just one refurbishment. Changing dies takes upwards of two hours during which time the line cannot operate

3 Pellet quality can be enhanced at lower temperatures that still permit the biosecurity benefits but where starch gelatinisation may not be sufficient on its own to improve pellet quality. This saves energy and speeds up throughput

“Selecting the right pellet binder

is cost effective in so many ways

and can be a real benefit in terms

of digestibility, biosecurity and

mill throughput thus making

a quality pellet binder pay for

itself many times over”

Grain&feed millinG technoloGy16 | may - June 2011

FEATURE

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In this issue:

• Synthesis of animal feed formulation techniques:

Linear and Non-Linear model

• Pellet production

to save energy,

improve feed efficiency

and safety

May 2011

• Choosing the right Hazard Monitoring System

• Pelleting: The link between practice and engineering

• Conditioning as part of the pelleting process

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