profitable farming of beef cows

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Profitable Farmingof Beef Cows

Editors: Steve Morris

and Duncan Smeaton

2009


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Profitable Farming of Beef Cows

Steve Morris and Duncan Smeaton


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Profitable Farming of Beef Cows

Written by:

Steve T. Morris, Massey University, Palmerston North, New Zealand and

Duncan C. Smeaton, AgResearch, Ruakura Research Centre, Hamilton, New Zealand

Special thanks are expressed to the following wri ters who also contributed:

• John Meban, Veterinarian, Gisborne part Chapter 4

• Chris Morris, AgResearch, Ruakura part Chapters 2 and 4;

sundry technical advice and accuracy checks• David Wells, AgResearch, Ruakura part Chapter 4

• John Pickering, Veterinarian, Whanganui part Chapter 5

• Dorian Garrick, Massey University part Chapter 6

• Kevin Stafford, Massey University Chapter 7

Editorial team:

Duncan Smeaton, Andy Bray, John Meban, Steve Morris, John Journeaux,

Peter Packard, Russell Priest

Printed by: Fusion Print Group Limited, Hamilton

Copyright © NZ Beef Council


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Preface

Professor Steve Morris from Massey University and Beef Production Scientist from

AgResearch, Duncan Smeaton, have, in this book, put together what could be rightfullyconsidered the New Zealand Manual for Beef Cow farming. So complete, thorough andpractical is it that both experienced farmers and new farmers embarking on the bovinetrail will find it as a guiding gospel, complete in its wisdom and forthright in the knowledgeit contains.

Until lately the beef cow has been unable to show just how valuable and profitable shetruly is. Devoted farmers of beef cows of all breeds have known by good old “seat of yourpants” farming that these Queens of the hills have been an integral part of the overallprofitability of their farms. It has been largely due to the eight Beef Focus Farms, in aproject financed by Meat and Wool New Zealand, and the work of the facilitator DuncanSmeaton and his group of scientists from AgResearch, that we now have figures to prove

just how well farmed cows and the relevant backup cattle, have guarded and increasedthe profit of sheep and other stock classes that farm with them. They often do this byeating some of the best feed available, but more often eating the very worst feedavailable too.

The ongoing desire to eat better tasting beef here in New Zealand and supply a bettertasting product to our customers abroad will continually require our beef farmers to haveexpectations of both stock and land that will be hard to fulfil. Confidence that what theyare doing is both technically and financially sound will be a big part in achieving this, andSteve and Duncan and their teams have surely provided a very important footing.

The New Zealand Beef Council had no hesitation in helping sponsor the publication of

this book as an effort in overcoming the somewhat alarming decline in beef cow numbersbeing farmed in New Zealand. Although at the time we were not in complete knowledgeof all the data that the focus farms were producing, we felt that as beef cows were thelynch-pin of the prime beef industry they needed some up-to-date reference material foruse by many sections of the farming industry as well as a reference for teaching.

As with most agricultural sciences in the modern world, beef breeding is a moving targetand improvements and refinements come upon us at a sometimes alarming rate. I’m surethat before too long some of the methods referred to here will have been updated andbrought into line with what-ever edict is coming down the pipe. I am equally sure that thevast amount of learning this publication has to offer can be relied upon as sound sciencefor many years to come.

John Wauchop, Chairman, NZ Sheep and Beef Council and Meat & Wool New Zealand.January 2009

Note to Readers:

There are 2 condition score (CS) systems in place for recording beef cow body condition orfat cover. One system operates on a 0 (emaciated) to 5 (fat) scale, the other systemoperates on a 1 (emaciated) to 10 (fat) scale. The systems are described in the book.

Whenever CS is discussed in the book, the value for the first system is noted, followed bythe value for the second system in brackets. For example, CS 2.0 (4).


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Table of Contents

Chapter 1: Introduction ...................... ...................... ......................... ...................... .............. 1

Summary ........................................................................................................................... 11.1. The importance of the breeding cow to the beef industry ......................... .............. 21.2. Beef breeding cow herds ...................... ....................... ...................... ................... 41.3. Breeding cows versus other sheep/beef enterprises .................... ...................... ... 7

1.3.1 Key points ..................... ...................... ......................... ...................... .............. 71.3.2 High vs. average performance cows .................. ......................... ...................... 71.3.3 Simplistic calculation of enterprise biological and gross margin performance .... 81.3.4 Calculating the full value of breeding cows on sheep and beef farms ................ 9

1.4. Beef herd sizes ........................ ...................... ...................... ......................... ...... 131.5. Further reading .................. ......................... ...................... ...................... ............ 14

Chapter 2: Weight of calves weaned and cow efficiency ...................... ................... ............ 15Summary ......................................................................................................................... 152.1 Introductory comments ....................... ...................... ......................... ................. 162.2 Setting and achieving calving date and calf weaning weight targets .................... 162.3 Optimum cow liveweight and cow efficiency ...................... ...................... ............ 182.4 Genetic selection for cow efficiency .................... ...................... .......................... 192.5 Other pathways to cow efficiency ..................... ....................... ...................... ...... 212.6 Cow liveweight and pasture damage ...................... ......................... .................... 212.7 Weaning date, calf age at weaning .................. .......................... ...................... ... 222.8 Further reading ........................ ...................... ...................... ......................... ...... 23

Chapter 3: Feeding beef cattle........................... ....................... ......................... ................. 24

Summary ......................................................................................................................... 24

3.1 Introduction .................... ...................... ....................... ......................... .............. 253.2 Energy requirements of cattle ..................... ......................... ...................... ......... 25

3.2.1 Requirements for maintenance .................. ......................... ...................... ...... 263.2.2 Requirements for pregnancy ...................... ......................... ...................... ...... 273.2.3 Requirements for lactation and calf growth ...................... ...................... ......... 283.2.4 Liveweight loss or gain ..................... ....................... ......................... .............. 29

3.3 Calculating feed requirements ....................... ...................... ...................... ......... 303.4 Management and nutrition of the beef cow ..................... ....................... .............. 31

3.4.1 General comments ......................... ...................... ...................... .................... 313.4.2 Post-weaning (weaning through to 4-6 weeks pre-calving) .................. ............ 313.4.3 Pre-calving (from 4-6 weeks pre-calving to calving) .................... .................... 323.4.4 Calving to mating ...................... ......................... ...................... ...................... . 333.4.5 Mating - weaning ...................... ...................... ...................... ......................... . 35

3.5 Matching nutritional requirements to the seasonal pasture supply pattern ........... 353.6 Supplementary feeding of beef cows ..................... ...................... ....................... 363.7 Assessing the adequacy of feeding .................. ....................... ...................... ...... 383.8 Condition scoring .................. ...................... ...................... ...................... ............ 393.9 Further reading ........................ ...................... ...................... ......................... ...... 41

Chapter 4: Reproduction in the beef cow herd .................... ......................... ....................... 42

Summary ......................................................................................................................... 424.1 Introduction .................... ...................... ....................... ......................... .............. 434.2 Potential reproductive rate .................... ....................... ......................... .............. 454.3 Reproductive management of beef cattle ..................... ...................... ................. 49


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4.3.1 Management and age at first calving of heifers ..................... ....................... ... 494.3.1.1 Critical minimum weight .................... ......................... ...................... ...... 524.3.1.2 Checklist for successfully mating heifers at 15 months ..................... ...... 52

4.3.2 Time and duration of calving ...................... ...................... ...................... ......... 534.3.3 Age of cow and reproductive performance .................... .................... .............. 544.3.4 Calving difficulty (dystocia) ..................... ...................... ...................... ............ 554.3.5 Post-partum anoestrus interval .................. ...................... ...................... ......... 584.3.6 Bull management ........................ ...................... ...................... ....................... 604.3.7 Pregnancy diagnosis ...................... ...................... ...................... .................... 62

4.3.7.1 Two methods of pregnancy diagnosis..................................................... 624.4 New reproductive technologies for use in beef breeding cows .................... ......... 63

4.4.1 Oestrus synchronisation ...................... ...................... ......................... ............ 644.4.2 Artificial insemination (AI) ................. ......................... ....................... .............. 644.4.3 Producing twin pregnancies ....................... ......................... ...................... ...... 654.4.4 Changing average calf sex ratio ...................... ...................... ......................... . 664.4.5 Cloning .................. ......................... ...................... ...................... .................... 674.4.6 DNA parenting ..................... ...................... ...................... ......................... ...... 67

4.5 Further reading ........................ ...................... ...................... ......................... ...... 68

Chapter 5: Cow health ......................................................................................................... 70

Summary ......................................................................................................................... 705.1 Grass staggers (Hypomagnesaemia) ..................... ...................... ...................... . 71

5.1.1 Overview ................. ......................... ....................... ......................... .............. 715.1.2 Magnesium supplementation ..................... ......................... ...................... ...... 72

5.2 Facial eczema ...................... ......................... ...................... ...................... ......... 755.3 BVD in beef cattle ...................... ...................... ......................... ....................... ... 76

5.3.1 Persistently Infected (PI) animals .................... ...................... ....................... ... 765.3.2 How does the virus affect cattle? .................... ...................... ....................... ... 775.3.3 Control of BVD ...................... ...................... ......................... ....................... ... 78

5.4 Nitrate poisoning................................. ...................... ...................... .................... 79

5.5 Bloat ....................... ...................... ...................... ...................... ......................... . 795.5.1 Overveiw ................. ......................... ....................... ...................... ................. 795.5.2 Management measures to reduce the risk of bloat ...................... .................... 80

5.6 Further reading ..................... ......................... ...................... ...................... ......... 80

Chapter 6: Genetics of calf production from beef cows ................... ....................... .............. 81

Summary ......................................................................................................................... 816.1 Introduction ................. ......................... ....................... ...................... ................. 82

6.1.1 Selection decisions ......................... ...................... ...................... .................... 846.2 Selection objectives ...................... ...................... ...................... ......................... . 87

6.2.1 Breeding objectives ..................... ...................... ...................... ....................... 876.2.2 Economic weights and values ...................... .......................... ...................... ... 886.2.3 The importance of future prices ......................... ...................... ...................... . 88

6.2.4 Selection criteria .................... ...................... ....................... ......................... ... 896.3 Estimated Breeding Values (EBVs) ..................... ....................... ........................ . 90

6.3.1 Growth EBVs ......................... ....................... ...................... ......................... ... 916.3.2 Reproduction EBVs ..................... ...................... ...................... ....................... 926.3.3 Carcass EBVs ....................... ...................... ....................... ...................... ...... 936.3.4 Additional EBVs available ................. ....................... ...................... ................. 946.3.5 Accuracy of EBVs ..................... ...................... ......................... ...................... . 956.3.6 Profitable use of EBVs ...................... ....................... ......................... .............. 96

6.4 Index Selection (BreedObject) ....................... ...................... ...................... ......... 976.4.1 Angus BreedObject ..................... ...................... ...................... ....................... 986.4.2 Hereford BreedObject ..................... ...................... ...................... .................... 99

6.5 Selecting breeding females ...................... ...................... ...................... ............. 1006.6 Evidence of genetic progress ................... ...................... ....................... ............ 102


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6.7 Choice of breed ......................... ....................... ...................... ...................... .... 1036.8 Breeding systems ...................... ...................... ....................... ...................... .... 1076.9 Crossbreeding ...................... ...................... ...................... ...................... .......... 108

6.9.1 Alternative crossbreeding systems........................ ...................... .................. 1096.9.2 Composite breeds .................... ...................... ...................... ........................ 1126.9.3 Alternating breeds over time ...................... ...................... ................... .......... 1126.9.4 Benefits of crossbreeding ................. ....................... ...................... ............... 1126.9.5 Disadvantages of crossbreeding .................. ....................... ...................... .... 113

6.10 Further reading ..................... ...................... ......................... ...................... ....... 114

Chapter 7: Beef cattle handling and yarding ........................................ ...................... ....... 116

Summary ....................................................................................................................... 1167.1 Introduction ................. ......................... ....................... ...................... ............... 1167.2 Cattle handling: Moving cattle ....................... ...................... ...................... ....... 1177.3 Working in yards ................... ......................... ...................... ...................... ....... 1187.4 Using forcing pens ..................... ....................... ...................... ...................... .... 1197.5 Working in races ................... ......................... ...................... ...................... ....... 1207.6 Yard design .................... ...................... ....................... ...................... ............... 1217.7 Conclusions .................... ...................... ....................... ...................... ............... 1227.8 Further reading ..................... ...................... ......................... ...................... ....... 122

Appendix 1: Condition scoring (CS) for beef cows ....................... ................... .................. 123

Appendix 2: Nutrient composition of commonly available feeds for cattle and sheep ......... 128


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Profitable Farming of Beef Cows Chapter 1: Introduction

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Chapter 1: Introduction

Summary

The beef cattle industry in New Zealand is made up of 4.3 million cattle of which

1.13 million (2008) are breeding cows. Traditionally, the New Zealand beef herd has been

based upon calves produced by breeding cows. An alternative system involves purchasing

4-day-old calves from the dairy herd and raising these as bulls or sometimes steers for

slaughter, or as replacement heifers in the beef breeding herd.

Achievable production objectives for a commercial beef breeding cow herd are to:

• Rear to weaning 90-95 calves per 100 cows mated each year for 63 days or less

• Grow suckling calves at greater than 1.0 kg/head/day

• Maintain a low death rate in the cow herd (2 to 3% per annum)

• Use the breeding cow herd to promote and maintain pastures.

At an assumed national average calving percentage (calves weaned/cows mated) of 80%,

the beef cow requires around 16 kg of dry matter per kg of calf weaned. The average beef

cow produces 0.30 kg calf weaned/kg cow weaning weight. In contrast, a high performing

cow produces 0.48 kg calf weaned/kg cow weaning weight (calculated as a 450 kg cowweaning 92% calves per cow mated, with calves growing at 1.1 kg/calf/day for 180 days)

and is more profitable. Very few farmers get all the components of high cow productivity

right all the time. Clearly it is a difficult business.

Breeding cows are often seen as being less profitable than other stock but this usually

excludes the effects of the beef cow on pasture quality. Recent results have shown that for

much of the year, many breeding cows consume poor quality herbage which is of little or no

value to other stock classes. On this poor quality feed, cows are more profitable than other

live stock classes. Other benefits include lower labour requirements. The cow needs to

play a complementary rather than competitive role to maximise these extra benefits. If a

farm produces only high quality pasture, then the pasture management benefits from cows

are likely to be low.


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Beef herd sizes are highly skewed because many small holdings (lifestyle blocks) run just a

few beef cattle. About 45% of beef cattle farms have less than 50 cattle and account for

only 7% of total beef cattle. At the other extreme, 6% of farms have over 500 beef cattle.In aggregate, these farms hold 41% of the total beef cattle.

1.1. The importance of the breeding cow to the beef industry

The beef cattle industry in New Zealand is based on a national herd of around 4.3 million

cattle. Considerable variation in the size of the national beef herd has occurred over the last

two decades. Beef cattle numbers peaked at 6.3 million in 1975 then subsequently

declined to 4.5 million in 1983. Currently (2008) the national beef breeding cow herd

numbers 1.13 million.

In New Zealand beef cattle and sheep are usually farmed together, and are complementary

to one another especially under hill country conditions. It is relatively easy for producers to

alter their mix of sheep and cattle to suit current economic conditions and preferences. The

main driving force behind this substitution is the relative profitability between cattle and

sheep. Growth in beef cattle numbers has occurred since 1983 but numbers today are

relatively static at around 4.5 to 5.0 million with fluctuation being mainly due to changes in

the number of dairy and dairy beef cross calves reared for beef production.

Traditionally, the New Zealand beef herd has been based upon the beef breeding cow

producing calves. Normally bull calves are castrated and raised as steers for slaughter

either on breeding or finishing farms. The latter are usually located on better class country.

Heifer calves replace the old and cull cows within the breeding herd and those that fail to

get pregnant. While this management system is practised around the country an alternative

system using calves from the dairy herd has come into prominence. Four-day-old calves

are purchased from the dairy herd and raised as bulls or sometimes steers for slaughter.

Beef breed x Friesian heifers are raised for replacements in the beef breeding herd. The

advantages for the bull system are two-fold. Firstly, there is no capital overhead tied up in a

beef-breeding herd, so more capital can be used for direct income generation. Secondly,

relatively more feed goes into production than maintenance, making this system more

efficient. Needless to say, some traditional beef cow herds are also very efficient.


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During the spring of the 2006 season the number of dairy calf retentions for beef production

was estimated at around 529,000, equivalent to around 38% of the total calves entering the

beef herd.

With an increasing percentage of the New Zealand beef herd being derived from the dairy

herd, the ratio of beef breeding cows and heifers in the national herd has declined from

36% in 1972-1973 to 27% in 2007-2008 with a resultant increase in “trading” or finishing

stock (see Table 1.1 where they are classified as “other cattle”). Unless retention of female

beef stock numbers increases, future growth and annual fluctuations in beef cattle numbers

will primarily be due to the number of dairy calves originating from the dairy industry that

are reared for beef production.

Another likely reason for the decline in breeding cow numbers is due to their perceived

poorer profitability. On a gross margin / kg DM basis, they are less profitable, but this

excludes the effects of the beef cow on pasture quality. In fact, the breeding cow is

significantly more profitable than other stock classes on poor quality feed. The cow needs

to play a complementary rather than competitive role to maximise these extra benefits.

About 78% of New Zealand’s beef herd is located in the North Island. While relatively

evenly distributed throughout the North Island, the Northland//Waikato/Bay of Plenty region

has 35% of the total herd. Table 1.2 lists the major beef cattle producing regions. A recent

change in cattle numbers is occurring in the lower part of the South Island where

substantial numbers of dairy beef calves are now being sourced from the increasing

number of dairy farms in the region.


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Table 1.1: Composition of the New Zealand beef herd (000) (as at 30 June).

Year 1973 1993 2008

Total Beef Herd 5,343 4,676 4,253

Breeding Cows 1,907 1,419 1,126

Other Cattle 3,436 3,257 3,127

Breeding cows as% of total

36 30 27

Source: Meat & Wool New Zealand Economic Service.

Table 1.2: Beef cattle numbers by local region (as at 30 June 2008)

Region Number of Beef Cattle (000) % of Total Cattle

Northland/Waikato/BOP 1,489 35

East Coast 1,060 25

Taranaki/Manawatu 509 12

NORTH ISLAND 3,058 72

SOUTH ISLAND 1,196 28

NEW ZEALAND 4,253 100

Source: Meat & Wool New Zealand Economic Service, paper P08031 25 July 2008.

1.2. Beef breeding cow herds

The breeding cow herd is dominated by two breeds, the Angus and Hereford. The heavier

European breeds began to be imported in the late 1960's and some, especially Simmental,

Charolais, South Devon and Limousin have made an impact as terminal sires, where, with

rare exceptions all progeny (both male and female) are sold for slaughter or to finishing

farms. There has also been an increased use of beef x dairy breeding cows to take

advantage of Friesian genes for higher milk and beef production. It is estimated (2007) that

the national herd consists of 23% Angus, 11% Hereford and 11% Hereford x Angus. Angus

and Hereford crosses would also contribute to a group classified as mixed crosses (36%)

while Friesian cross (12%) and others (7%) make up the rest (derived from data from

Meat & Wool New Zealand Economic Service).


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Achievable objectives for a commercial beef breeding cow herd are to:

• Rear to weaning 90-95 calves per 100 cows mated each year for 63 days or less

• Grow suckling calves at greater than 1.0 kg/head/day• Maintain a low death rate in the cow herd (2 to 3% per annum)

• Use the breeding cow to promote and maintain pasture quality

The national average calving rate (the number of calves weaned as a % of cows mated) is

82% (range 79% to 86%) and has remained at this level for the last 35 years. Age of first

calving is usually 3 years although approximately 30% of all heifer replacements now calve

at 2 years of age. The top third of herds in any year have an average 90% calving rate or

better. There is potential for increased reproductive performance of the beef herd within the

constraint of a natural ovulation rate of 1.0 in cattle.

Because the overall output of a breeding cow herd is dependent on both weaning

percentage and weaning weight of the calf, these are often combined into a term called cow

productivity.

However, the total feed consumed by large cows is greater than that of small cows. To

take account of this the term weight of calf weaned per cow joined (i.e. the productivity)

divided by the cow liveweight (usually autumn or weaning weight but some farmers prefer

to use winter liveweight) is a commonly used measure of biological efficiency in the beef

breeding cow herd.

As a general rule, smaller cows that wean heavy calves (in excess of 50% of their damautumn liveweight) are more efficient. This is probably easier to achieve with some form of

crossbreeding where a larger terminal sire breed is crossed with a smaller dam breed.

The difference in annual feed consumption (kg dry matter/head/year) for three different cow

liveweight types (small, medium and large) means small cows rearing small calves can be

just as efficient and profitable as large cows rearing large calves. Table 1.3 illustrates that

there are a range of cow types that can give similar productivity and returns. If each of the

cows in Table 1.3 rears 50% of their own autumn liveweight to sale as weaner calves they

Productivity =no. of calves weaned x Av. weaning weight

no. of cows joined with bull

Efficiency =Productivity

Cow liveweight


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are then all equal in terms of $ return per kg of feed eaten or per stock unit. It is high

productivity irrespective of cow size that makes a beef cow herd profitable

Table 1.3: Seasonal liveweights and production data for three different beef breeding

cow types and calculations of efficiency and profitability (note liveweights exclude the

weight of conceptus). The calculations assume that small vs. large weaners are worth the

same per kg liveweight.

Small Medium Large

Weaning (kg) 430 470 550

Mid-winter (kg) 380 420 500

Pre-calving (kg) 380 420 500

Mating (kg) 410 450 530

Calf wean wt (kg) 215 235 275

Feed eaten per cow (kg DM) 2880 3131 3657

Number of cows 100 92 79

Number of calves

(at 80% CW/CM*)80 73.6 63.2

Kg DM/kg Calf weaned 16.7 16.8 16.6

Return/kg feed ($) 0.186 0.187 0.187

Gross margin ($ / SU) 105 107 108

* Calves weaned per cows mated.

If a beef cow herd is not productive then the other benefits of keeping this class of stock

need to be large to compensate (i.e. improved sheep performance). These other benefits

have proven difficult to quantify although recent trial results described below provide more

information.


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1.3. Breeding cows versus other sheep/beef enterprises

1.3.1 Key points• In single enterprise analyses comparing profitability of breeding cows, finishing

cattle and breeding ewes, breeding cows usually appear less profitable. However,

this analysis does not take into account the other benefits cows may provide within

the farm system.

• Cows can play a valuable complementary role in managing pasture quality on sheep

and beef farms but this is difficult to value. Results from the recently completed

Meat & Wool New Zealand Beef Focus Farm project have shown that for much of

the year, many breeding cows consume poor quality herbage which is of little to no

value to other stock classes. On this poor quality feed, cows are more profitable

than other live stock classes. Other benefits include less labour requirements.

1.3.2 High vs. average performance cows

Accumulated figures for breeding cows on New Zealand hill country farms (Meat & Wool

New Zealand Economic Service) indicate that the average beef cow herd is performing well

below potential in that:

• 80 to 82 calves are weaned per 100 cows mated

• Calves grow at a little over 0.8 kg per day from birth to weaning (accurate figures

not available)

• 0.30 kg calf weaned/kg cow liveweight is produced (calculated as a 500 kg cow

weaning 82% calves per cow mated, with calves growing at 0.90 kg/calf/day for

180 days)

The above implies that one in five cows are non productive, and the pasture these animals

consume therefore represents a lost opportunity. This is partially offset if farmers cull empty

cows at weaning but this has an added cost in terms of higher replacement rates.


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In contrast, high producing cows in the recent Beef Focus Farm Project funded by

Meat & Wool New Zealand (2008):

• Weaned in excess of 92 calves per 100 cows mated

• Grew their calves at 1 to 1.2 kg/head/day from birth to weaning

• Produced 0.48 kg calf weaned/kg cow weaning weight (calculated as a 450 kg cow

weaning 92% calves per cow mated, with calves growing at 1.1 kg/calf/day for

180 days).

• Were more profitable (Table 1.4).

High performing cows are often beef x dairy cross cow mated to a terminal sire thereby

taking advantage of hybrid vigour. In this system, all calves are finished for beef, withreplacements sourced from outside the herd.

Trial results indicate that the high levels of performance described above are routinely

achieved on some farms with the cow still carrying out her complementary role of pasture

management, provided the cow can regain any lost weight during the crucial calving to early

mating period. Even so, very few farmers get all the components of high cow productivity

right all the time. Clearly it is a difficult business. The prioritisation of other stock classes

over breeding cows is often the root cause of poor cow performance. Farmers who achieve

high levels of cow performance while using cows for pasture management have learnt the

critical elements that allow these two conflicting goals to be met.

1.3.3 Simplistic calculation of enterprise biological and gross margin

performance

When various sheep and beef systems are compared on a single enterprise basis, results

such as shown in Table 1.4 can be derived.


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Table 1.4: Comparison of four single-enterprise systems modelled using Farmax, each

on the same pasture growth curve.

Average **performance

cow

High **performance

cow

HighFertility

ewe1yr bullsystem

GM* $/ha 449 680 717 796

GM c/kg DM 6.6 8.9 8.6 10.7

Net LWG/ha 350 490 591 908

kg DM/kg LWG 20 16 13 8

* Gross Margin

** As described in section 1.3.2

Average performing beef cows are less productive and profitable than some other

enterprises largely because of their high maintenance requirement and the apparently

non-productive period from weaning to just before calving in terms of product gain/kg DM

eaten. If cows could rear and wean two calves via twin pregnancy that would cause a

quantum leap in productivity and probably profit, but that is mostly outside current

technology. Table 1.4 demonstrates that finishing systems, such as the bull system shown,

are more efficient biologically, and also currently more profitable. High fertility ewes are

also relatively efficient, and are often very competitive financially.

However , the above gross margin analysis can be misleading because it takes no account

of the complementary role that one stock class provides for another within a full farm

system.

1.3.4 Calculating the full value of breeding cows on sheep and beef farms

It is generally recognised that cows play an important role in maintaining pasture quality on

many farms, benefiting other live stock. Cows can also lose a lot of weight during poor

winters, freeing up feed for other less resilient stock. This effect was studied in the recent

Beef Focus Farm Project funded by Meat & Wool New Zealand (2008). On the Northland

farm in this project, cows spent summer, autumn and winter cleaning up behind other live

stock. The quality of the pasture being consumed by the cows was monitored on a monthly

basis for the cows, and for the other stock the cows were complementing. On one of the


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blocks on the farm, the cows predominantly grazed on medium to steep hill land (with

approximately one quarter of the pasture having a Kikuyu base) and the cows followed

behind ewes and lambs. The other block was rolling to medium hill land with approximately90% of the pasture Kikuyu based and cows grazed among young cattle.

The grazing residual results showed that the cows were restricted most, during

summer/autumn and early winter, when they were cleaning up behind the other stock

classes (Figure 1.1) but that in spring, they fared much better.

Figure 1.1: Average post-grazing herbage mass of breeding cows and other stock

classes (Northland Focus Farm).

In general, the quality (MJ ME/kg DM) of pasture offered to the cows was poorer than that

grazed by the other live stock (Figure 1.2). The quality of the diet offered to the cows

changed with season to a greater extent than that of the other live stock classes, reflecting

the ability of management to prioritise better quality feed to other live stock classes during

seasons when poor quality feed was present (summer and autumn). Over the 3 years of

the study, the average metabolisable energy concentration (ME) of pasture consumed by

cows was 8.8 vs. 10.3 MJ ME/kg DM for the other stock classes the cows were

complementing.


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Figure 1.2: Average metabolisable energy content of pasture offered to the breeding

cows and other livestock classes.

Cow liveweights and condition score peaked during summer in response to good feed

availability during spring and early summer (Figure 1.3) and declined again during late

summer and autumn. Despite the poor quality of feed and loss in cow liveweight, each year

the calves grew at greater than 0.6 kg/day during the late summer/autumn period and

greater than 0.8 kg/day over the whole lactation period. This demonstrates the ability of the

cow to buffer the calf, through liveweight loss and milk production during this period on poor

quality pasture.

Figure 1.3: Average cow (conceptus-free) liveweight and condition score (on a 1 – 10

scale).

Observations on a second focus farm in the same project as reported above, in Southland,

showed similar buffering effects by the cow.


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If the poor quality herbage is not consumed by cows then it either will be consumed by

another stock classes or it will decay. In the Focus Farm Project, the former option was

tested using the computer models Q-Graze and Farmax (see Further Reading). The weightgain or loss of 2-year-old bulls fed the same quality of pasture as the cows was calculated.

As with the breeding cows, the 2-year bulls were predicted to gain weight during spring and

early summer and then lose weight during autumn and early winter (Figure 1.4).

Figure 1.4: Estimated two year bull liveweight gain (kg/head/day) if fed on the same

herbage as the breeding cows on the Northland farm, as calculated by Q-Graze. The

change in value of 2-year bulls ($/head/day) is based on liveweight change and seasonal

store market values.

Total liveweight gain by the bulls for the year was calculated at only 38 kg. The analysis

showed a total annual increase in bull value of $128 per cow equivalent. In contrast, cows

were calculated to be returning $363 per head (after losses). That is, the cows returned a

gross margin income of $235/cow more than the bull equivalent system could have done on

the same feed. A similar exercise on the Southland farm showed a similar result.

No one would normally farm finishing animals in the way shown above, but it does illustrate

the fact that the pasture that the cows are consuming has very little value to other live stock

classes for a large portion of the year. In fact there are times when this herbage could be

considered a liability rather than an asset.


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If a farm produces only high quality pasture, (though intensive subdivision etc) then the

above benefits due to running cows are likely to be much less and returns will be closer to

the enterprise results in Table 1.4. In this situation, cows should be replaced by higherreturn stock classes. However, it should be noted that intensive subdivision is not feasible

on many hill country farms.

1.4. Beef herd sizes

Beef herd sizes are highly skewed because of the many small holdings (lifestyle blocks)

which run a few beef cattle. Figure 1.5 shows that small holdings make up the majority of

farms with beef cattle. However, these small holdings have a relatively small proportion of

the total beef herd. For example, 22% of the beef holdings have less than 10 beef cattle.

In aggregate, these holdings have just over 1% of the total beef cattle. About 45% of beef

cattle farms have less than 50 cattle and account for only 7% of total cattle. This group of

farms are likely to be less responsive to industry conditions than the larger more

commercial farms. At the other extreme, 6% of farms have over 500 beef cattle. In

aggregate, these farms have 41% of the total beef cattle.

Figure 1.5: Beef cattle herd size distribution by % of cattle and % of farms, June 2002

Source: Statistics New Zealand (2002) Agricultural Production Census – Note that this is

the most recent information available.


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1.5. Further reading

AgResearch. 2002. In “Pasture quality: Principles and management, The Q Graze Manual.

A reference document to accompany The Meat New Zealand pasture quality

workshops, Published January 2002 Meat New Zealand, PO Box 121, Wellington,

pp 1-26.

Farmax. A decision support model for livestock farms. www.farmax.co.nz

Marshall, P.R.; McCall, D.G.; Johns, K.L. 1991. Stockpol: A decision support model for

livestock farms. Proceedings of the New Zealand Grasslands Association. 53:

137-140.

Meat & Wool New Zealand Economic Service. Various reports, available onwww.meatandwoolnz.com

Smeaton, D.C. 2003. Profitable Beef Production. A guide to beef production in

New Zealand. Published by the New Zealand Beef Council. ISBN: 0-473-09533.5.

Smeaton, D.C.; Boom, C.J.; Archer, J.A.; Litherland, A.J. 2008. Beef cow performance and

profitability. Proceedings of the 38th seminar of the Society of Sheep and Beef

Cattle Veterinarians NZVA, pp 131- 140.


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Profitable Farming of Beef Cows Chapter 2: Weight of calves weaned and cow efficiency

15

Chapter 2: Weight of calves weaned and cow efficiency

Summary

The total weight of calves weaned is the key production output of the breeding cow herd

and is the end result of many input factors. About 70% of the variation in weaning weight of

calves is due to differences in milk production of the dam. To achieve high calf weaning

weights cows must be well fed before and after calving. A high level of feeding after calving

is also necessary for a high conception rate at rebreeding. Date of weaning should depend

on feed supply.

The best cow for hill country is a medium sized cow that weans a high proportion of its

liveweight in calf weaning weight. The optimum liveweight of mixed-age Hereford x Friesian

cows is estimated to be 430 to 450 kg at mating. In a trial, cows at optimum weights, and

rearing a live calf, weaned calves at 180 days of age that were 52% of their mother’s

liveweight at mating. Including losses due to empty cows and calving losses, the ratio

dropped to 44%. The average rate of calves weaned per cow mated in this case was 82%.

Selecting to improve the efficiency of feed conversion in a cow herd has been proposed as

an alternative to selecting for growth rate. Feed conversion ratio is a measure of the

amount of feed eaten per unit of bodyweight gain or carcass weight gain. Net feed

efficiency refers to variation in feed intake between animals beyond that related to

differences in growth and liveweight. Selection for this should reduce herd feed costs.

Ranking animals on net feed efficiency requires measuring differences in their feed intake,

liveweight and growth rate over a defined test period.

Selecting cows for lifetime productivity at first weaning can be advantageous but requires

tagging of calves with their birth mothers. The process is complex, but the gains are there iffarmers are willing to invest the time.

Efforts have been made to improve cow productivity through multiple suckling via one

means or other, but commercial success remains elusive because of technical and

biological limitations. In the meantime, the best objectives are to run cows at optimum

weights, take maximum advantage of their ability to gain and lose weight to support milk

production and to maintain pasture quality, achieve high pregnancy rates and survival and

take maximum advantage of genetic opportunities and hybrid vigour.


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2.1 Introductory comments

The total weight of calves weaned by the herd is a key production output of the

breeding cow herd.

It is a reflection of:

• Reproductive success; clearly, empty cows do not wean a calf

• Feeding levels of cow and suckled calf

• Cow and calf genetics, hybrid vigour

• Cow and calf health

• Age at weaning (for comparative purposes, a standardised weaning age of 180 days

is often used).

The weaning weight of an individual calf from a cow is dependent on the above factors and

also more specifically:

• Cow milk production (in turn dependent on numerous factors)

• Age of dam

• Age of calf at weaning, affected in turn by:

• Calving date

All the above are discussed in the various chapters of this book. The material below

discusses management aspects of integrating these factors.

2.2 Setting and achieving calving date and calf weaning weight targets

The ability to wean heavy calves has become progressively more important in conventional

single-suckled breeding-herds because of the trend towards selling cattle for slaughter at a

younger age. This means that growth to weaning represents a higher proportion of total

growth to slaughter.

Calf weaning weight targets will be specific to the farm in question but a minimum liveweight

gain target for a suckled calf on hill country should be 1.0 kg/calf/day. Typically in

New Zealand it is less than this, particularly if the cow is expected to do a lot of pasture

quality management work. Most beef calves are weaned at around 5 to 7 months of age

resulting in calf weaning weights in the range of 180 to 240 kg (assuming a 35 kg birth

weight). Some farmers achieve weights of up to 280 kg/calf. The importance of a

condensed calving (target of 70% of cows calving in the first 21 days of calving) within an


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appropriate calving period (where the planned start of calving is synchronised with pasture

supply) cannot be underestimated because of its effect on calf weaning weight and cow re-

breeding performance. Many commercial beef herds calve too early in the spring. Theusual sign for this is a slow start to calving (less than 50% calved in the first 21 days of

calving) which compromises calf weaning weights and cow rebreeding performance.

The rate of growth of the suckling calf largely depends on the cow’s milk supply, which in

turn depends on the food available to the cow. Some research suggests that about 70% of

the variation in weaning weight of calves is due to differences in milk production of the dam.

A calf can consume 10-15% of its liveweight as milk each day. A 50 kg calf can drink 7-8 kg

milk per day and at this rate will grow at 1.0 kg liveweight gain/day. As the calf grows, its

capacity to drink milk increases and there are obvious advantages if the cow can increase

her milk production to match this demand. A calf at 120 days weighing 150 kg could

consume around 15 kg of milk. It is highly unlikely a cow would produce that much milk at

that stage and so the calf gets its extra nutrients by consuming pasture.

To achieve high calf weaning weights, cows must be well fed before and after calving. A

high level of feeding after calving is also necessary for a high conception rate at rebreeding.

Experience suggests that a feed budget should allow for a cow to eat in excess of 12 kg

DM/day from the day of calving. How this will be achieved depends on the date of calving,

and may require feed saved from late winter. Cows will often buffer their calves against

underfeeding in early lactation by losing liveweight to maintain calf growth. However, this

can not happen in poor conditioned cows (CS 2 (4) or less), so it is therefore desirable to

have cows in a condition score of 2.5 (5) or better at calving. A recent trial at Massey

University indicated that for heifers, a sward (pasture) height of 6 cm is sufficient in the first

month after calving increasing to 10-12 cm during the second month.

Date of weaning should depend on feed supply (it often depends on labour availability and

sale date). If there is ample feed, there is little to be gained from early weaning unless there

is an opportunity to use the cows in a mob for pasture control or preparation for other

classes of stock. However, if hill country pastures dry out badly in summer, calves could be

weaned and put onto what fresh pasture is available and the cows fed hard rations to

relieve grazing competition.


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2.3 Optimum cow liveweight and cow efficiency

The best cow for hill country is a medium sized cow that weans a high proportion of its

liveweight in calf weaning weight. The cow needs to be in good condition at weaning so

she can then use her excess body condition as “supplementary feed” over the winter

months. In fact, cows should be at their maximum liveweight and condition at weaning

indicating they have eaten as much as possible of the excess spring-summer feed that

usually occurs on hill country properties.

It is possible for cows to wean calves (at 180 days age) that weigh 50% to 60% of the cow’s

weight (compared to 35% to 45% on average). This is neither a new objective nor is it easy

to achieve. In a project at Whatawhata Research Centre (Smeaton and others 2000) theoptimum liveweight of mixed-age Hereford x Friesian cows was estimated to be 430 to

450 kg (Figure 2.1). Anecdotally, many farmers run their cows at weights significantly

heavier than this, thereby foregoing productivity advantages and running some risk of

surplus fat in the udder which can jeopardise milk production (especially in heifers). At

optimum weights in the Whatawhata project, cows rearing a live calf weaned calves at 180

days of age that were 52% of their mother’s liveweight at mating. Including losses due to

empty cows and calving losses, the ratio dropped to 44%. In summary cow productivity is

extremely sensitive to:

• Cow liveweight relative to calf weaning weight

• Pregnancy rate

• Cow survival

• Calf survival, mostly around the calving period

Figure 2.1: Illustration of optimum liveweight for Hereford x Friesian breeding cows

Source: Reworked data from Smeaton and others (2000).


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2.4 Genetic selection for cow efficiency

(other breeding traits are discussed in Chapter 6)

Traditionally, beef producers improve their herds by selecting for growth. Growth is an easy

and economical trait to measure and is moderately heritable. Selection for growth traits has

resulted in faster growing cattle, however it has also resulted in the introduction of some

correlated undesirable traits such as increased birth weights leading to calving difficulties,

delayed sexual maturity and increased herd maintenance requirements associated with the

feed costs of larger animals.

In most beef cattle production systems, researchers have established that 65% to 85% of

total feed intake is required by the breeding cow herd, and that half of the total feed intake is

required just to maintain cow liveweight. The costs of maintaining the breeding cow herd is

clearly an important factor determining the efficiency of beef production.

Despite its economic importance, farmers in New Zealand do not usually assess the cost of

feed for their farming operation. The complementary roles of beef cattle on sheep farms

complicate the economic assessment of feed efficiency in New Zealand’s mixed livestock

farming systems as discussed elsewhere. However, as profitability is a function of both

inputs and outputs, there is a need to consider avenues for reducing inputs in order toimprove efficiency of production and increase profits.

By selecting to improve the efficiency of feed conversion in a herd, the producer can strive

to improve the efficiency of converting feed to gain, rather than concentrating on growth

alone. Different measures of the efficiency of growth have evolved over the years because

of the complex nature of feed use in the animal. The most commonly used definitions to

describe the efficiency of growth are:

Feed Conversion Ratio (FCR)

This is a measure of the amount of feed eaten per unit of bodyweight or carcass weight

gain. Since feed is the numerator, FCR should be minimised. Common values for growing

ruminants grazing pasture are around 7-10 (kg fed consumed / kg liveweight gain) whereas

pigs and poultry aim for values less than 2. The term Feed Conversion Efficiency (FCE) is

also often used but the more correct term is FCR as it is a ratio (i.e. feed eaten per unit of

gain)


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Efficiency of Feed Utilisation

Efficiency of feed utilisation is simply the reciprocal of FCR. The important point to

remember is that more efficient cattle will have a lower FCR and a higher efficiency of feed

utilisation. When comparing efficiencies from different studies or farms, calculations need

to clearly state the measures (units) of inputs and outputs used.

Residual Feed Intake

An issue that is of considerable practical interest is the extent to which individual animals

are more or less efficient than would be expected. Animals can be compared using net

feed conversion efficiency or the residual feed intake. More efficient cattle can

theoretically be found within any desired cattle weight range, and selection will notnecessarily increase mature size.

Net feed efficiency (NFE) refers to variation in feed intake between animals beyond that

related to differences in growth and liveweight. Consequently it is expected that selection

for improved NFE may reduce herd feed costs with little or no adverse changes in growth

performance. Ranking animals on NFE requires measuring differences in their feed intake,

liveweight and growth rate over a defined test period. A high NFE bull will consume less

feed than expected over the test period and have a lower (negative) net feed intake. A low

NFE bull will consume more feed than expected over the test period and have a higher

(positive) net feed intake. An animal’s expected feed intake is predicted from the test

groups’ average feed requirements for a particular growth (say 1 kg/head/day) and

liveweight (say 300 kg). An animal’s net feed intake is simply the difference between its

predicted feed intake and its actual feed intake.

Selecting for efficient cows within a herd (usually when the first calf is weaned)

Calf weaning weight, adjusted for calf sex, calf sire breed and year-of-birth of dam, has a

moderate repeatability as a dam trait1

of 0.37 (if adjusted for date of birth of calf), or 0.29 (ifunadjusted for date of birth). Both of these traits, again as dam traits, are heritable, and the

New Zealand heritability estimates were 0.26 and 0.19, respectively (Morris and others

1993). Cow weights, adjusted for age, or year of birth, are highly repeatable (0.54), and

moderately heritable (0.26).

1 Trait: A measured genetic feature or characteristic


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Selecting cows for a productivity objective is probably best achieved by using a linear index

of calf weight and cow weight (e.g. A x calf weight difference from the adjusted mean, minus

B x cow weight difference from the adjusted mean), rather than by using a ratio of the twoadjusted weights. It is acknowledged that tagging and some recording is required, to get

the best out of this procedure (i.e. calf-to-dam links, calf sex, date of birth), and if done on a

commercial property, comparisons would need to be done within cow breeds or breed

crosses, because of differing amounts of hybrid vigour expected. Managing separate

grazing groups around or after calving may also complicate interpretation of the results.

It is also important to remember that the sire contributes to herd productivity, i.e. the sire of

the calf and also the sire of the cow. The Breeding Values of candidate sires need to be

taken into account when purchasing service sires and when breeding/purchasing heifer

replacements. The above process is rather complex, but the gains are there if farmers are

willing to invest the time and the recording costs.

2.5 Other pathways to cow efficiency

Various efforts have been made to improve cow productivity either via twinning or by using

embryo transfer to put high growth rate calf genetics into small, high milk producing cows,

but commercial success remains elusive because the technology required remainsimmature or inadequate at several stages of the production cycle (see Chapter 4 also).

Therefore, the right system at present would aim to: run cows at optimum weights; take

maximum advantage of their ability to gain and lose weight to support milk production; use

cows to maintain pasture quality; achieve high pregnancy rates and survival; and take

maximum advantage of genetic opportunities and hybrid vigour.

2.6 Cow liveweight and pasture damage

Heavy cows are more likely to cause pasture damage and pugging on wet or steep hill

country than light animals. In wet weather on steep hill country, damage can be severe,

increasing the risk of erosion and weed invasion although this problem is manageable with

care. This is not discussed in detail here (see Further Reading for more information).


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2.7 Weaning date, calf age at weaning

The main advantage of early weaning appears to be in retaining cow body condition. If the

previous management has been correct, this should not be an important issue. However in

case of droughts, and a requirement to graze cows off the farm as part of the drought

management strategy, early weaning can be practiced.

Weaning time is often determined by managerial convenience and timing of weaner sale

dates in the district. Farmers often like to wean on the day of these sales so calves are

trucked to the sale straight off their mothers looking in their best condition. However, if

calves are not being sold at weaning, then weaning date can be related to feed supplies. In

one recent study (Figure 2.2), calves weaned late (9 months of age) had a significant liveweight advantage (55 kg) over calves that were weaned at the normal time (6 months of

age). Most of this advantage was retained through to 18 months of age. This advantage in

weight gain was shown to be due to milk intake. This study also demonstrated that weaned

calves are more susceptible to internal parasites than calves that are still receiving milk.

Figure 2.2: Mean calf liveweights for calves weaned at normal time (20 March), late

weaned (26 June), or late weaned with no suckling from 20 March on.

Source: Boom and others (2003).


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2.8 Further reading

Boom, C.J.; Sheath, G.W.; Vlassoff, A. 2003. Interaction of gastro-intestinal nematodes

and calf weaning management on beef cattle growth. Proceedings of the

New Zealand Society of Animal Production 63: 61-65.

Thorrold, B. 2008. Management to minimise environmental damage, Ch 10 In Profitable

beef production, A guide to beef production in New Zealand. A book, Ed

D.C. Smeaton. Published by Meat & Wool New Zealand, Beef Council. Third

Edition. Meat & Wool New Zealand, PO Box 121, Wellington.

Smeaton, D.C.; Bown, M.D.; Clayton, J.B. 2000. Optimum liveweight, feed intake,

reproduction, and calf output in beef cows on North Island hill country,

New Zealand. New Zealand Journal of Agricultural Research. 43: 71 - 82.

Smeaton, D.C.; Harris, B.L.; Xu, Z.Z.; Vivanco, W.H. 2003. Factors affecting commercial

application of embryo technologies in New Zealand: a modelling approach.

Theriogenology. 59: 617-634.


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Profitable Farming of Beef Cows Chapter 3: Feeding beef cattle

24

Chapter 3: Feeding beef cattle

Summary

This chapter describes the feed and grazing management requirements of breeding cows.

Beef cattle should be fed at levels appropriate to their production target and the long term

sustainability of the farming enterprise. Due to the variability of pasture growth and the

demands of other livestock classes, it is rare for a farmer to get feed allocation absolutely

correct. In calculating feed requirements for cattle, the requirement for maintenance,

liveweight gain, milk production, and pregnancy are estimated separately and then added

together. Requirements for cattle, based on these metabolic processes are provided. In

practice many people calculate metabolisable energy (ME) feed requirements from feedtables or unwittingly by using farm management models that calculate intake as part of

modelling their farm systems.

The feed management strategy for a beef cow-breeding herd is determined by a balance of

feed supply patterns, competing resources and market requirements. There are major

benefits from running beef cows on hill country farms because of their flexible feed demand

which can be aligned with the seasonal pasture growth curve. An additional benefit is their

ability to assist in the management of pasture quality. An important attribute of the hill

country beef cow is her ability to transfer feed from the late spring/summer period to winter

via stored body fat. If this is managed successfully, it is often unnecessary to feed

supplements to cows.

For simplicity the annual nutritional requirements of spring calving beef cows are divided

into the following periods: Post-weaning; Pre-calving; Post-calving; Post-mating. Both

liveweight and body condition scoring are useful aids to checking the feeding and

management of the herd at critical periods of the yearly production cycle. Condition

scoring, seemingly less precise than weighing, is a practical way of monitoring the animals.

The main management decision that affects the matching of the cow’s needs to pasture

production is the time of calving. Since most of New Zealand’s beef cows are run on farms

where sheep contribute the majority of stock numbers, the time of calving will also be

influenced by the needs of other stock classes, usually lambing ewes.


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3.1 Introduction

Beef cattle should be fed at levels appropriate to their production target and the long term

sustainability of the farming enterprise. Due to the variability of pasture growth and the

demands of other livestock classes, it is rare for a farmer to get feed allocation absolutely

correct. Pasture growth rate predictions can differ from actual because of variable climatic

conditions. Forage crops other than pasture are not used widely, but supplementary feed of

various types (hay, silage, concentrates) may be used in times of feed shortage during

winter or dry summers.

The management on sheep and beef cattle farms ranges across the spectrum from

extensive, where conservative stocking rates are used and the animal’s body weight acts asthe main buffer between pasture production and feed requirements, through to intensively

managed and planned systems where the farmer makes decisions on a daily basis to

achieve this balance. In the more intensive systems, management to increase animal

production is focused on lambing and calving liveweight targets, weaning date, flushing, and

the timing of the sale of store lambs, weaners, cull ewes, cull cows and finishing steers or

bulls.

The points made above highlight the fact that most beef production is in conjunction with

other livestock classes. When evaluating a beef cattle operation consideration must always

be given to what other stock classes the cattle are complementing or competing against at

various times of the year, and how their performance will change if the beef system is

changed.

3.2 Energy requirements of cattle

Feed requirements represent the amount of feed which must be consumed in order to

sustain a defined level of production. For any specified level of performance(e.g. pregnancy, liveweight gain or milk production), sufficient nutrients and energy must be

supplied to the animal tissues to meet metabolic demands. Requirements can be

conveniently expressed as metabolisable energy (ME) because with most pastures, energy

is the most limiting factor for a given level of production. Other nutrients such as protein,

minerals and vitamins (except where there is a known deficiency) are almost always

present in adequate amounts. However, in some instances e.g. young growing animals,

protein may be limiting, especially on low digestible mature type pastures.


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The major determinants of the energy requirement of grazing livestock are:

• liveweight and body condition

• stage of pregnancy

• level of milk production

• rate of liveweight gain or loss

• composition of liveweight gain or loss

• level of activity in eating and movement

• possible effects of climate

• sex of animal

• walking distance and climbing hills

Obviously it is difficult to include all these variables in tables of ME requirements that are

easy to use. In calculating feed requirements for cattle, the requirements for maintenance,

liveweight gain, milk production, and pregnancy are estimated separately and then added

together. The energy requirements of growing cattle are not covered here. Refer instead to

the Further Reading section (Nicol and Brookes, 2007; Smeaton 2007).

3.2.1 Requirements for maintenance

The ME requirement for maintenance is the amount of ME that must be supplied to provide

energy needed for essential body functions. If this energy is not supplied in the diet it must

be obtained by mobilising body tissue, predominantly fat.

As liveweight increases, so too does maintenance energy requirement (Table 3.1), with

every 100kg increase in liveweight requiring an additional 11 MJ ME/day. Increased

grazing and activity costs on hard hill country are significant. These maintenance

requirements are significantly higher than those used by Geenty and Rattray (1987).


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Table 3.1: The metabolisable energy requirement (MJ ME/cow/day) for maintenance of

beef cows. Source: Nicol and Brookes (2007).

Liveweight (kg)

Land class 300 400 500 600

Easy hill - 55 66 77

Hard hill 50 65 75 -

Notes:

Add/subtract 7% per MJ ME for diets below/above 10.5 MJ ME/kg DM.

Add 15% for adult bulls.

A guideline requirement for maintenance can be given as:

0.62 MJ ME/kg liveweight 0.75 for cows on easy hill country

0.70 MJ ME/kg liveweight 0.75 for cows on hard hill country

3.2.2 Requirements for pregnancy

The amount of energy used for both maintenance and growth of the foetus and the products

of conception depends on:

• Days from conception. The greatest increase in requirements occur in the last third

of pregnancy

• Number of offspring (twins rarely exceed 1% of births in beef cattle)

• Size of the foetus

Guideline requirements for pregnancy for calves of varying birthweights are shown in

Table 3.2. These values are additional to the maintenance requirements of the cow.


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Table 3.2: The metabolisable energy requirement of beef cows (MJ ME/cow/day) for

pregnancy (in addition to maintenance requirement). Source: Nicol and Brookes (2007).

Calf

birth weight (kg)

Weeks before

calving

Total for

Pregnancy

-12 -8 -4 0

MJ ME/cow/day MJ ME

30 6 11 20 34 1700

40 9 15 26 45 2300

50 11 18 32 55 2800

Notes: Add these to the maintenance requirement of the cow.

Adjust proportionately for pregnancy rate of the herd, for example,

Pregnancy rate = 95%, ME for 40 kg birthweight, 4 weeks pre-calving

= 0.95 x 26 = 25 MJ ME/cow/day.

3.2.3 Requirements for lactation and calf growth

The ME requirement for milk production depends on:

• Total milk yield (litres)

• Milk composition - because milk varies in concentration of fat, protein and lactose,

the ME requirement per litre will also vary.

It is extremely difficult to know the milk production of beef cows but it will usually range from

5-10 litres/day for single suckled cows. In addition and as a guideline, 5.8 MJ ME/kg milk is

assumed.

The costs of lactation and calf growth (Table 3.3) are estimated as 60 MJ ME/kg calf

weaning weight (slightly less for very light calves). Assumptions have been made about the

proportion of the requirements of the calf which has been supplied by milk and grazing.

However, this ratio does not markedly affect the total ME requirements for calf growth to

weaning.


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Table 3.3: The metabolisable energy requirements of beef cows and their calves during

lactation (in addition to cow maintenance requirements). Source: Nicol and Brookes (2007).

Calf weaningweight (kg)

Months after calving Total forlactation+1 +3 +5 +7

MJ ME/cow + calf/day MJ ME

150 35 45 55 55 8700

200 40 55 65 75 12000

250 50 70 85 95 15000

300 60 80 100 115 18000

Notes: Add these figures to cow maintenance requirement. (See Table 3.1)

Adjust proportionately for weaning %, for example

85% weaning, 200 kg calves, 5 months = 0.85 x 65 = 55 MJ ME/cow/day.

Add/subtract 8% MJ ME for diets below/above 11.0 MJ ME/kg DM.

3.2.4 Liveweight loss or gain

When animals lose weight, mobilisation of body tissue releases energy which therefore

does not have to be supplied by the diet. In lactating animals, this energy can be used to

maintain milk yield, even though the animal is losing weight. The figure often used for

New Zealand beef cows is 55 MJ ME required per kg of LWG gain, and 1 kg of liveweight

loss in mature cows substitutes for around 30 MJ ME of herbage intake. Thus the net cost

of losing and gaining a kg of liveweight is 25 MJ ME/kg of liveweight.

Condition Score (CS) and liveweight change

Target condition scores are often given for particular stages of the production cycle. When

using the 0 to 5 CS scale, one unit change in CS is equivalent to 75 kg for a 500 kg

Hereford cow. On the 1 to 10 scale, the weight change per unit is about 40 kg

The approximate quantities of ME per 1 unit change of condition score (Scale 0-5) range

from 4815 MJ ME/CS for a non lactating cow of with a CS of 2.0, to 5650 for a non lactating

with a CS of 4. For lactating cows it is 3450 (CS 2.0) and 4500 (CS 5.0) MJ ME/CS

change. These values would be about half for the 1 to 10 scale. Condition scoring is

discussed in more detail later in this chapter.


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3.3 Calcul ating feed requirements

In practice most people calculate ME feed requirements in computer models without even

realising it. Less commonly, they may estimate them from feed tables such as in Table 3.1

to 3.4. Requirements in kg DM/head/day can be determined from these tables once a value

of the energy (ME) content of feed is known. Pasture typically contains 8 to 12 MJ ME/kg of

DM depending on the quality of pasture. Note that some feed tables are quoted in kg DM.

These should be used with caution when using them for pastures of varying energy content.

Table 3.4 provides an example of how the previous information can be used to compute the

annual metabolisable energy requirements for breeding cows with different levels of

productivity on either good or hard hill country. Note the greater (23%) feed requirements ofthe more productive cow in the better environment compared to that of the cow in the hard

hill country.

Table 3.4: The annual ME requirements of beef cows in hard and easy hill country.

Source: Nicol and Brookes (2007).

Specifications Hard hill Easy hill

Liveweight (kg) 400 550

Weight loss/gain (kg total) 30 30Calves born/cow joined 92 97

Calf birth weight (kg) 30 40

Calves weaned/cow joined 86 90

Calf weaning weight (kg) 175 250

ME requirements (MJ ME)

Maintenance 365 x 65 = 23725 365 x 72 = 26280

Weight loss/gain 30 x 25 = 750 30 x 25 = 750

Pregnancy 0.92 x 1700 = 1565 0.97 x 2300 = 2230

Lactation and calf growth 0.86 x 10350 = 8900 0.90 x 15000 = 13500

Total annual (MJ ME/year) 35000 42750

Notes:

Maintenance requirement from Table 3.1

Net cost of loss and regain of weight is 25 MJ ME/kg (Para 3.2.4).

Total requirement for pregnancy from Table 3.2 and number of calves born (NCB).

Total requirement for lactation and calf growth from Table 3.3 and number of calves weaned


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3.4 Management and nutrition of the beef cow

3.4.1 General commentsThe management strategy for a beef cow-breeding herd is determined by a balance of feed

supply patterns, competing resources and market requirements. There are major benefits

from running beef cows on hill country farms because of their flexible feed demand which

can be aligned with the seasonal pasture growth curve. An additional benefit is their ability

to assist in the management of pasture quality. In this respect, they play an important role

on kikuyu pasture in Northland and brown-top dominant swards elsewhere. Hill country

farmers marketing weaners in the autumn will often put in place a strategy to cope with

calving ahead of the spring pasture growth, in order to supply the market with older, and

therefore larger, weaners. Farmers marketing progeny in the following spring or autumn, or

finishing the weaner steers themselves, have the flexibility of being able to calve at a more

appropriate time in relation to their pasture growth curve. An appreciation of the pasture

growth curve of a farm is fundamental to the management of any pasture based production

system. When calving before the spring pasture growth flush, the cow is placed in a more

competitive rather than a complementary position with other livestock classes that might

also be able to utilise that same scarce feed.

For simplicity we can divide the annual nutritional requirements of mature spring calving

cows into the following periods: Post-weaning; Pre-calving; Post-calving; Post-mating. Both

liveweight and body condition scoring are useful aids to checking the feeding and

management of the herd at critical periods of the yearly production cycle. Condition

scoring, while seemingly less precise than weighing, is nevertheless a practical way of

monitoring the animals.

3.4.2 Post-weaning (weaning through to 4-6 weeks pre-calving)

Weaning of beef calves normally occurs at 5 to 7 months of age. It can be carried out

successfully at 4 months (this can be an appropriate drought management strategy)

provided appropriate provision is made for post-weaning feed for the calf. In the beef cow

calendar this leaves 5 months of the year that beef cows are low priority stock and can

function as 'work horses' eating rank pasture and controlling shrub re-growth provided they

were in good condition at weaning . During this time, priority can be given to other classes

of livestock and cows become one of the few groups available that can be restricted in the

interests of pasture development and utilisation. This is a major justification for maintaining


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a breeding cow herd on hill country. Not only has it significant advantages for the farm as a

whole, but it has in fact been shown to be beneficial for the cows to lose around 10% of

their liveweight in the post-weaning period.

Cows losing that order of liveweight have increased longevity and suffer no reduction in

performance; provided their nutritional requirements are met in the pre- and post-calving

periods and lost liveweight is regained. Cows fatter than condition score (CS) 3.5 (7 on 1 to

10 scale) at calving are more prone to calving difficulties and to metabolic disease. A

reduction in intake around calving should not be carried out too rapidly with fat cows, as

they can suffer from hypomagnesaemia if subjected to sudden severe restrictions in intake.

Some farmers rotationally graze their cows behind the ewes in a winter rotation during this

period. In such situations cow intakes are very low e.g. Angus cows can eat as little as

3-3.5kg DM/day. This highlights their efficiency and supports the theory that an efficiently

managed beef cow could have a true winter stock unit cost of 3.5 stock units compared to

the commonly accepted value of 6 to 7. Minimising cow feed requirements during

maintenance periods can have a significant impact on overall feed efficiency and therefore

profitability on a hill country sheep and cattle farm. This should be a consideration when

establishing appropriate stock unit equivalents.

3.4.3 Pre-calving (from 4-6 weeks pre-calving to calving)

Cows that have lost in the order of 10% body weight post weaning need to regain some

condition pre-calving and will need to be on a rising plane of nutrition up to and through

mating. If they do not, there is a risk they will be too weak at calving and prone to metabolic

problems, and calf losses can be high (of the order of 10%-20%).

A relatively short period (4 weeks) of high nutrition (6-8kg DM intake/cow/day) is usually

sufficient. Note that the calf is gaining at 250 grams/day in utero during the last month of

pregnancy. If feed is available, liveweight gain on cows will be easier to achieve pre-calving

than during early lactation and is unlikely to have any significant effect on calf birth weights,

except at extremes of feeding levels. If cows calve at CS 2.5-3.0 (5 to 6) it will make the

mating condition target of 3.0 (6) a lot easier to meet.


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While poor pre-calving nutrition and body condition score can exacerbate post-calving

under-nutrition problems, priority in terms of feed allocation should be given to the

post-calving period. This can be achieved by shedding cows out from a moderate plane ofnutrition to a high plane as they calve, by strip grazing, shifting into saved feed at the start

of calving or calving onto spring growth. Some farmers, by calving late enough are able to

set stock cows amongst ewes and lambs at calving. Whatever system is used to apportion

feed, CS at calving is critical because it affects CS at mating, one of the most critical points

in cow management.

3.4.4 Calving to mating

Research suggests that Angus and Friesian cross beef cows need to eat in excess of 12 kg

DM /day from the day of calving through to mating. Larger breeds will require

proportionately more. How this feed demand is met will depend on the time of calving, but

even herds calving close to their pasture growth curve will need some feed carried forward

from late winter. The area chosen for calving should be of easy contour and free of hazards

like creeks, tomos (underground holes) and swamps as these cause significant calf losses.

Post-calving nutrition is critical for several reasons:

• Cow survival - the majority of cow deaths from hypomagnesaemia occurpost-calving and peak in the second week of lactation as the milk demands of the

calf increase. Provision of high quality pasture above 2500kg DM/ha (12 cm high)

is the key to its prevention. In some conditions, magnesium supplementation may

be required for a period during and after calving. Other metabolic conditions that

can occur at this time of the year are milk fever and ketosis. However they play a

very minor role in beef cow losses and are also prevented by correct cow condition

at calving and post-calving nutrition.

• Calf growth rates - cows under-fed in early lactation will buffer their calves by

losing liveweight to maintain milk production. However, with high milk producing

Hereford x Friesian cows at a CS of 2.5 (5) or better at calving, it may be

necessary to restrict feed for the first 3-4 weeks post-calving. This is because the

calves are unable to consume all the milk produced by these high producing cows.

A recent trial indicates that a pasture sward height of 6 cm is sufficient for

beef x dairy heifers during the first month of lactation, increasing to 10-12 cm

during the second month of lactation.


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Calves should gain at least 1.0kg/hd/day while suckling their dams. Milk makes up

a large proportion of their diet up to 12 weeks of age after which they can consumeup to 50% of total diet as grass.

• Subsequent cow pregnancy rate and calving pattern – There are two aspects to

consider:

1. Whether the cow is pregnant or not

2. When the pregnancy was achieved

Cows fed in excess of

profitable farming of beef cows

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