GENETICS Russell Priest, Meat and Wool Innovation Ltd, Feilding

Transcription

1 CHAPTER 8 GENETICS Russell Priest, Meat and Wool Innovation Ltd, Feilding Summary Genetics is an economically important component of beef production systems. Estimated breeding value (EBV) is a commonly used predictor of the value of an animal as a parent for a particular trait (e.g. 600 day liveweight). In the absence of any other information, the best prediction of how the progeny of two parents will perform is determined by averaging the EBVs of the parents, for the particular trait in question. This represents then average performance of progeny above a base EBV of zero (the breedaverage EBV for the trait, when the population was first genetically assessed). There are currently 19 different EBV traits being generated. In a simple cattle-finishing operation, the most important trait to consider is growth rate. The faster an animal grows, the less time it takes to reach slaughter or mature weight. This improves feed conversion efficiency (FCE) or ratio (FCR). Genetic effects on FCE operate through their impacts on mature size. In recent years, there has been increased interest in genetic differences between animals in their Net Feed Efficiency (NFE). NFE refers to the variation in feed intake between animals, beyond that related to differences in growth rate and body weight. EBVs for NFE have been developed by Breedplan and are available for industry use. No single breed possesses all the desired attributes for beef production. Crossbreeding utilises the difference between breeds and captures the benefits of hybid vigour. Use of terminal breeds is a feature of this. The performance of different breeds is described. Relative to the Angus, some breeds have 30% greater growth potential but have only 81% of its carrying capacity. Always consider how a breed may perform in a particular environment. In general, the European terminal-breed crosses have better growth rates, carcass conformation and higher yields of saleable meat, at the same fat level, compared with British breeds such as Angus and Hereford. The sex of an animal affects FCE. Bulls grow faster than heifers and steers but have a higher maintenance requirement. Overall bulls are more efficient. Relatively speaking, bulls grow 40% faster than heifers, but can only be stocked at 78% of the carrying capacity. Steers are in between. 104 CHAPTER 8 Genetics

2 Age is important. Younger animals have more tender meat and also have better FCE because of lower maintenance requirements and the laying down of muscle rather than fat. Gene marker technology is emerging as a means of identifying difficultto-measure traits in live animals and will complement EBVs. Introduction Genetics, along with health and nutrition are the three most economically important components of beef production systems. While the effects of health and nutrition are easily observed, genetic effects are far less obvious. To achieve maximum production, all three must be considered. In this chapter, genetics will be discussed in relation to: Estimated breeding values (EBVs) Mature liveweight, growth rate and feed conversion efficiency (FCE) Breeds and crossbreeding Sex Age Technologies available to meet industry requirements. Dairy industry integration Sourcing animals Estimated Breeding Values What is an Estimated Breeding Value (EBV) and how is it calculated? An EBV or Breeding Value (BV) is a genetic prediction of the average performance of an animal s progeny or a prediction of how an animal is going to perform as a parent. EBVs are expressed in the units of the particular trait. For example, 600-Day Weight is expressed in kg, Scrotal Size is expressed in cm and Calving Ease is expressed as a percentage figure. An EBV can be generated for any trait as long as there is variation within the trait and the trait is of known heritability. Development of an EBV starts with collecting raw data (basic information) on a group of animals, which have been treated the same. The raw data is then adjusted to ensure that all animals within the group are compared on a level playing field. For instance, weaning weights have to be adjusted for the date of birth of the calves and the age of the cows. Once the adjustments are made, the computer then: Calculates an average performance figure for the group for each trait Compares each individual animal within the group with this average, so that each animal has a performance figure, which is above or below the average Multiplies this difference from the average, for each animal, by the known heritability of the trait CHAPTER 8 Genetics 105

3 The resulting calculation for each animal represents the animal s within group EBV for the particular trait being considered. Example: A group of Angus 20-month bulls has been run together since birth and has been treated the same. These animals represent a management or contemporary group as they have all been given an equal opportunity to produce. The group is weighed for 600-Day Weight and their individual weights are adjusted for age, to put them all on the same level playing field. Assume the average adjusted weight for the group is 700kg. If one of the heavier animals within the group (Turbo) has an adjusted weight of 760kg then he is 60kg above the group average. This 60kg is made up of weight due to the activities of Turbo s genes (genetic effects) and that due to feeding and animal health etc (environmental effects). In assessing an animal s breeding potential (EBV) we are only interested in the genetic part of the production, because this is the only part that we can influence through selection. To find out how big this genetic production is, we multiply the total production advantage Turbo has over the average animal within his group i.e. 60kg, by the genetic strength of the 600-Day weight EBV (its heritability, which is 0.3 or 30%). This will give Turbo s within herd EBV for that trait. It is assumed that the average EBV for 600-Day Weight for the group is 0kg. In short, Turbo s within group EBV for 600 Day Weight is : ( ) kg 0.3 = +18kg The computer then uses performance information from Turbo s relatives in other management groups, as well as known genetic relationships between traits, to fine tune this basic within group EBV so that Turbo can be directly compared with all other animals within the same evaluated population. How does an EBV relate to profitability? The offspring of a bull with an EBV for 600-day weight of 130kg will be 65kg heavier and return in the region of 15% more profit than the progeny of a bull with an EBV of zero. This takes into account the additional feed eaten by the higher performing animals, and assumes the two bulls are mated to cows of similar genetic merit. It does not allow for the higher-growth-rate animals attracting early season premiums, which can further improve profitability. There are currently 19 different EBVs being generated. Therefore it is vitally important, when considering what EBVs to pursue, to only target those traits that the processor currently pays for. The finisher should also consider any other traits that they think may receive some sort of monetary recognition in the near future. Each individual beef finisher may have different genetic 106 CHAPTER 8 Genetics

4 requirements for stock; therefore it is unwise to promote genetic recipes without pointing out their shortcomings. In a simple finishing operation, the most important trait to consider is growth rate, as the sooner the cattle meet target liveweights: The more efficient the animals are, in terms of conversion of grass to beef The sooner monetary returns are received The more likely the animals are to attract early-season premiums The more likely the producer is to avoid that period of the year when there is a dramatic decline in pasture quality, with correspondingly poor cattle growth rates. The New Zealand schedule of payments for beef producers is reasonably straightforward. There is price differentiation based on dentition, which separates heifer from cow; and sex, which differentiates between females, bulls and steers; and age, to specify bobbies (veal). Farmers of finishing cattle are paid primarily for carcass weight, with a small premium being offered for muscling. They therefore need to target the carcass weight EBV (if this is not available, the 400- and 600-day weight EBVs) very strongly, and to a much lesser extent, the Eye Muscle Area (EMA) EBV, and fat EBVs when selecting sires or animals to finish. If the finisher is also breeding the cattle for finishing, attention needs to be paid to the calving ease EBV, if it is available, or the birthweight EBV to ensure reasonably trouble-free calving. Finishers of steers and heifers should also be targeting high growth rate EBVs, particularly for 400-day weight. However, they should also be aware that their cattle may need to be finished before the second winter. That is, they should be starting to lay down fat at 18 to 20 months to meet the specifications at slaughter of 4 to 12mm of carcass fat depth. Progeny of cattle that rank highly for the 400-day weight EBV and not so highly for the 600-day weight EBV, demonstrate the maturity pattern required to meet this specification. Minor consideration should be given to the EMA EBV to achieve the slight premium offered for muscling. To summarise: An EBV is a prediction of the genetic value of an animal as a parent. The average genetic performance of the offspring of a cow and bull will be determined by the average of the EBV s of the parents (compared to a base EBV of zero). For example, an average animal from parents with 400-day EBV s each of +60kg and +20kg respectively will itself be 40kg heavier at 400 days of age than an animal from parents each with EBV s of zero. However, environmental influences may alter the expression of this. CHAPTER 8 Genetics 107

5 EBVs can be used as another tool to select stock for specific finishing systems. Beef finishers may have different finishing objectives, therefore it is unwise to use genetic recipes to select stock, without considering individual cases. Mature Liveweights Mature liveweight can be defined as the weight of a normally grown animal possessing a mature skeleton with, or adjusted to, a chemical body fat content of 20%. Generally, there is a strong positive relationship between mature liveweight and growth rate. Since growth rate is the most important trait in achieving slaughter weights in as short a time as possible, it should feature strongly in any consideration of profitable beef finishing systems. However, not all producers want to run cattle with maximum growth genetics, as these may mature too late, thereby possibly requiring a second winter of growth to meet market requirements (Figure 1). In this case, the advantages gained by rapid growth would be offset by the cost of maintaining a large animal over the second winter. The challenge for the finisher is to select the animals with the appropriate growth characteristics for their production system. Figure 1: Growth patterns for early and late maturing beef animals. The late maturing animal is born heavier, grows faster and finishes at a higher weight and older age. 108 CHAPTER 8 Genetics

6 Feed conversion ratio or efficiency Definitions of terms Feed Conversion Ratio (FCR) is a measure of the amount of feed eaten per unit of liveweight gain or carcass weight gain. Since feed is the numerator, FCR should be minimised. Common FCR values for fast growing cattle are 7-10 whereas pigs and poultry aim for values less than 2. FCR is also often called Feed Conversion Efficiency or FCE. (See Chapter 5) Efficiency of Feed Utilisation is simply the reciprocal of FCR and since feed is the denominator, it should be maximised. The important point to remember is that more efficient animals will have a lower FCR or FCE and a higher efficiency of utilisation. When comparing information from different studies, it is important to be clear which relationship is being used and also to be clear about the measures (units) of inputs and outputs used. Growth versus maintenance and FCR or FCE The conversion of feed into carcass weight can be considered under two headings. 1. Growth Versus Maintenance 2. Genetic Factors In terms of the first item, quite simply, the faster an animal grows, the quicker it reaches slaughter or mature weight so that less time is required to maintain the animal. This improves FCR or FCE. This aspect of FCE is discussed in detail in Chapter 5. Genetic factors affecting growth and FCE Genetic effects on FCE operate through their impacts on the mature size of the animal. As shown in Figure 1 above, late maturing breeds of animals or animals with higher weight EBV s are born heavier, grow faster and finish at a higher weight. They therefore tend to have a better FCE. In recent years, there has been increased interest in measuring genetic differences between animals in their Net Feed Efficiency (NFE). NFE refers to the variation in feed intake between animals, beyond that related to differences in growth rate and body weight. Consequently, it is expected that selection for improved NFE may reduce feed costs with little or no adverse changes in growth performance. Ranking animals on NFE requires the measurement of differences in their feed intake, body weight 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 group s average feed requirements for a particular growth rate (say 1kg/head/day) and CHAPTER 8 Genetics 109

7 liveweight (say 300kg). An animal s net feed intake is simply the difference between its predicted feed intake and its actual feed intake. A Massey University trial is evaluating selection for NFE under New Zealand pasture fed conditions. Selection for improved NFE is being assessed in conjunction with improvement in other traits such as liveweight gain and maternal traits. The difference in EBVs between the high NFE and low NFE bulls used in the 2001 matings of the trial translated to an expected 13% difference, when the bulls progeny weighed 300kg, grew at 1.0kg/day and consumed 8 kg of DM. EBVs for NFE have been developed by Breedplan and are available for industry use. Breeds and crossbreeding No single breed possesses all the attributes to satisfy all the requirements of the producer, the finisher and the processor. Crossbreeding utilizes the differences that occur between breeds and captures the production benefits (5-8%) resulting from hybrid vigour. There is also considerable variation within breeds, in some traits, to enable significant genetic progress to be made towards achieving marketplace requirements. For example, in the 2002 Transtasman Genetic Evaluation Report for one of New Zealand s maternal breeds, there was 78kg difference between the animal with the highest carcass weight (CWT) EBV and that with the lowest. At $3.00/kg CWT this represents a massive financial difference of $235. Hybrid vigour or heterosis In many cases, crossbred progeny perform better than the average performance of their parent breeds. This phenomenon is known as hybrid vigour or heterosis and occurs where unrelated breeds or lines are crossed. The extra performance described above, through hybrid vigour, is simply the recovery of production losses that have occurred through inbreeding in the parental breeds. In general, the more highly inherited a trait is, the less hybrid vigour occurs. Breeds can be divided roughly into terminal, maternal, dual-purpose and composite categories. Terminal breeds These have high mature liveweights, high growth rates, lean, high-yielding carcasses showing excellent conformation but poor ability to marble. Examples include the Charolais, Limousin and Chianina breeds. Maternal breeds Maternal breeds of cattle generally have moderate mature weights and growth rates and reach maturity at an earlier age. They tend to lay down both external and intramuscular fat more readily, do not have such high carcass yields and 110 CHAPTER 8 Genetics

8 show as much muscularity as the terminal breeds. Examples include the Angus, Hereford and Shorthorn breeds. Dual purpose breeds These are breeds which have the ability to perform well in a wider range of productive traits than those breeds in the above two categories. Examples include the Friesian, Simmental, Gelbvieh and South Devon breeds. Composite breeds These are breeds that have been developed, in recent years, by combining the superior attributes of a number of different breeds into one composite breed, while capturing and retaining some of the hybrid vigour resulting from the crosses. Performance of different breeds Most breed effects can be explained by differences in mature liveweight and the composition of liveweight gain. The growth potential of New Zealand crossbred cattle is shown in Table 1, where a purebred Angus is set at 100. European (sometimes called Continental or Exotic) cross cattle such as Charolais, Simmental and Maine-Anjou crosses have the greatest growth potential. Calves out of Hereford x Friesian (HxF) cows are heavier at weaning and have a greater growth potential than calves out of Angus and Hereford cows (the so-called British breeds) mated to common sires. In considering the above, it is important to remember that variation within breed can be as great as the differences described in Table 1. The growth potential data in Table 1 show that weaning weights of large Continental cross HxF calves will be around 30% greater than Angus purebreds and they will grow about 30% faster after weaning. However, because of the size difference, carrying capacity will be only about 80% of that of Angus. Cattle of large mature size tend to grow faster, although under New Zealand conditions, the differences between breeds are not as great as elsewhere, where animals are more intensively fed. In choosing which breeds to finish, consideration needs to be given to: The environment in which the animals are going to be run. The requirements of the processor (customer). Traits that are going to be financially rewarded. Carrying Capacity. Breed availability. CHAPTER 8 Genetics 111

9 Table 1: Relative growth potential and carrying capacity of New Zealand breed crosses. Sire breed Dam Breed Growth Carrying Potential Capacity Angus A Murray Grey A and H Hereford A and H Limousin Chianina A and H South Devon Blonde d Aquitaine Friesian Charolais Simmental Maine-Anjou Angus HxF Hereford HxF Limousin Chianina HxF Blonde d Aquitaine South Devon Friesian Charolais Simmental Maine-Anjou A = Angus, F = Friesian, H = Hereford The environment in which the animals are to perform Always consider how the breed may perform in an environment and also the breed s feeding requirements. To limit damage to soil structure, consider running cattle with lower mature liveweights. In a harsh environment where feed is restricted, a more traditional breed may perform better than the faster growing European crosses. The requirements of the processor customer The requirement is always to produce what the customer wants and be aware of: Who is the customer? 112 CHAPTER 8 Genetics

10 What are the specifications, for the product the farmer will be supplying? What are the traits they will pay the producer for? Traits that are going to be financially rewarded At present in New Zealand, meat processing companies base their schedule payments on carcass weight, fat content, muscling, maturity and sex of the animal. Carrying capacity All things being equal, breed and breed crosses with greater growth potential must be run at lighter stocking rates as described in Table 1 above. Comparisons of different breeds and their crosses Table 2: Ranking of Friesian cross steers compared with straight Friesian (shown in bold in the Table) for carcass weight, and lean meat yield when compared at similar carcass weight. Table 2 shows how different breed crosses can be ranked for carcass weight. There are also differences in yield at the same carcass weight. Table 3 compares straightbred and crossbred Angus steers slaughtered at 20 months and shows CHAPTER 8 Genetics 113

11 that both carcass weight and yield vary. By shifting from a Hereford x Angus cross to a Charolais x Angus, there is both a lift in carcass weight (28kg), and yield (1.8%). Table 3: Comparison of Angus cross steers with straight Angus for carcass weight and lean meat yield. If European breed cross bulls or steers are being farmed, there is an added incentive to sell on a carcass weight basis because of the 1.5-2% improved dressing out rate obtained from these animals. Producer options If a producer wishes to improve carcass weight, while controlling fat depth, the easiest option is to use sires of larger mature size (Table 4). The use of a European breed of bull will also improve carcass muscling, although producing such a crossbred animal may not always be appropriate, particularly under difficult grazing conditions where intake is likely to be restricted. Where a breeder cannot change the breed, carcass fatness can be reduced by slaughtering at a lighter weight. However, there will be some cost associated with doing this, as the carcass value in c/kg will decline. 114 CHAPTER 8 Genetics

12 Table 4: Ranking of Angus crossbred steers compared with straight Angus, for carcass weight and fat depth as absolute and relative values. Summary of breeds and crosses In general, the European terminal breed (or exotic) crosses have better growth rates, conformation and higher yields of saleable meat, at the same fat level, compared with the British breeds such as Angus and Hereford. However, these advantages do not necessarily influence profitability of finishing, where calves are brought in, provided they are purchased at the appropriate price. For calf producers who sell weaners, the choice of a large European terminal sire mated to Friesian cross cows, will produce a much more valuable product at weaning and at any subsequent stage, than a purebred Angus. CHAPTER 8 Genetics 115

13 Sex The sex of an animal affects FCE in three ways: 1. Bulls have a maintenance requirement about 15% higher than that of steers, with little difference between steers and heifers. This means that at maintenance or low liveweight gain (below about 0.3kg/day) the feed requirement of bulls is actually greater than that of steers of the same liveweight ( Figure 2). Figure 2: The feed requirements (MJ ME/day) for 300kg liveweight bulls (late maturing) and steers (early maturing) at different growth rates. Figure 2 also illustrates why the feed intake of bulls and steers of the same liveweight is often not very different. For an intake of 60 MJ of ME (around 5kg DM), bulls will grow at around 0.8kg/day and steers at around 0.6kg/day. 2. Sex can affect FCE through the composition of liveweight gain. Weight gain in bulls contains more protein and less fat than that of steers and a similar difference exists between steers and heifers. This effect of sex is also illustrated in Figure 2, where the greater costs (steeper line) of liveweight gain in steers represents the greater fat content in their liveweight gain. Consequently, on this basis, the FCE of bulls at higher liveweight gain will be better (less feed/kg of gain), than that of steers. 3. The third difference between the sexes, which can contribute to FCE, is their potential growth rates, with bulls having a 20% greater potential 116 CHAPTER 8 Genetics

14 than steers and steers having a 20% greater potential than heifers (of the same breed or breed cross). Refer to the comments earlier on the effects of growth rate on FCE. The relative carrying capacity of bulls and steers is accordingly lower than heifers (see Table 5 below). Table 5: Relative growth potential and carrying capacity of bulls steers and heifers (Heifers = 100). To summarise this section: Bulls have a 20% greater growth potential than steers and a 40% greater growth potential than heifers. Bulls have a 15% higher maintenance requirement than steers, with very little difference between steers and heifers (all animals being of the same breed and liveweight). Bulls have a better FCE than steers, which in turn have a better FCE than heifers of the same breed and liveweight except at low liveweight gains. At low growth rates (below about 0.3kg/day), bulls have a greater feed intake than steers and heifers of the same liveweight. Sex of the animals, run in a beef finishing system, is only one of a number of factors that influence the profitability of the system. Age Age is important in a pastoral-based beef production system because: Meat is more tender in younger animals The older an animal becomes, the more fat it lays down and the more yellow it becomes, (particularly with Jersey cattle) Younger animals convert feed to meat more efficiently, because they have a lower maintenance feed requirement (due to their lighter weight) and CHAPTER 8 Genetics 117

15 they are at an earlier stage of maturity (are laying down a greater percentage of lean meat to fat) In terms of FCE, one should avoid carrying finishing stock through a second winter before processing. Ideally, animals need to reach target finishing weights by early in their second summer, before pasture quality declines and prior to their second winter. Genetically, the finisher is looking to target progeny from sires, which have the highest possible carcass weight EBV, while ensuring that they have the finishing ability to meet market demands for fat cover and muscling. Animals that have a very high EBV for 400-day weight but which display reduced growth in their 600-day weight EBV (the growth curve tapers off, displaying advancing maturity), are generally those that meet the above criteria. The type of animals the finisher needs to avoid (particularly if they need to be finished by months of age) are those that rank highly both at 400-day and 600-day weight. These animals are generally later maturing and are better suited to being finished at 30-plus months of age. If left entire, they are also ideal as finishing bulls, where fat depth is not an issue. But remember, these are only generalisations and that the bull represents only half of the genetic equation. The maturity pattern of the dam breed should also be considered. For example, current market requirements for steers may well be able to be met at 20 months of age by finishing cattle out of a very early maturing maternal breed (that may be too fat, at this age, as a purebred) and a very late maturing continental breed (that may be too lean as a purebred at this age). Technologies to meet industry requirements As meat markets become more sophisticated and product specifications become tighter, the beef industry will need to develop strategies to assist in meeting these requirements. There are an increasing number of technologies becoming available that will assist in producing animals to meet market specifications. Currently these are: Genetic information on animals in the form of EBVs: as discussed above. Customized EBV indices focusing on profit Gene marker technology Sexed semen and embryos EBVs are defined above and provide estimates of how animals will perform as both parents and offspring, in a particular trait. If the market specifications are for carcasses of a certain weight and finish, animals with the appropriate EBVs can be selected and used in the breeding programme to produce the required result or product. For example, dairy farmers require beef-bred bulls with easy 118 CHAPTER 8 Genetics

16 calving characteristics and/or bulls that leave calves with short gestation length. Compare this with beef finishers that need animals with good growth genetics and in many cases the ability to finish by 18 to 20 months of age. There is a potential conflict here in that animals which grow fast, tend to have a high birth weight. This is a major contributor to calving difficulty and so a compromise will usually be necessary to satisfy both dairy and beef farmer. EBVs provide the tools for making such a compromise. Customized Indices quantify the relative profit that can be generated by similar breed bulls used in a specified production system, and as such are a more sophisticated form of EBV than are individual trait EBVs. An Index is therefore an EBV for Profit and that profit is related to a particular production system. For example, there may be an Index for bulls that are to be used in the dairy industry (a Dairy Beef Index), and it will describe the relative profit that a particular bull can generate on each progeny per cow mated. In producing the Index, the computer considers the economic importance of all the appropriate traits involved in a particular production system. The traits will be adjusted accordingly. For example, there may be a Local Trade Index and an Export Index, to cater for the different processor specifications of each market. It is unlikely that a bull, which ranks very highly in a Dairy Beef Index, will also rank highly in an Export Index or a Local Trade Index. Therefore a Customized Index ranks bulls on profitability in a defined production system. Gene Marker Technology enables difficult-to-measure traits, such as tenderness in live animals to be identified, in some cases quantified, and will complement EBVs in producing animals to meet market specifications. For example, in identifying the gene that controls marbling in beef, it is now possible to determine whether a particular animal has one or two copies of that gene, which will in turn enable a prediction to be made of the degree of marbling in that animal s progeny. Recently a Brisbane Company, Genetic Solutions, has used genetic marker research to develop two tests, GeneSTAR Marbling and GeneSTAR Tenderness, which can detect the degree of marbling and tenderness in the meat of a live beast. Both products are now available on the market. Sexed Semen will enable cows to produce calves of a predetermined sex. This will have major implications for both the beef and the dairy industries. Dairy farmers will be able to generate replacement females from their top-producing cows, and ensure that all others have potentially more valuable male calves for the beef farmer to finish. At present, this technology is expensive and not used commercially. CHAPTER 8 Genetics 119

17 Dairy industryintegration With nationally declining numbers of beef breeding cows, beef cattle finishers are increasingly turning to the dairy industry to source their finishing stock. Most dairy farmers regard surplus dairy and beef x dairy calves as a byproduct of bringing their cows into milk. In addition, they generally avoid any bulls that are likely to cause calving difficulties. Although dairy cows are a potentially very efficient means of generating animals for finishing, the calving difficulty mentality is a major hurdle that the beef industry must come to terms with if beef x dairy calves are to be produced from this source. For successful integration of the two industries to be achieved, the dairy farmer must: Be aware of, and have a basic understanding of, the genetic information that is available in the beef industry and how to use it. Be aware that most AI dairy bred bulls have breeding values for growth but it is uncertain how useful this information is for beef producers. Be prepared to tag all their calves at birth and identify the breed of the parents. Realise that using a beef-bred bull without the appropriate genetic information may result in calving difficulty and not achieve the desired type of animal for beef finishing. Be serious about using a beef-bred bull to generate beef x dairy stock as opposed to using a bull merely to bring cows back into milk production. For the above to happen, the financial rewards must be enjoyed by all parties. The beef rearer and finisher must be aware of the genetic information in dairy and dairy x beef animals and be prepared to pay a premium to dairy farmers to secure those animals with superior genetics, to make it worthwhile for the dairy farmer. Only then will the dairy farmer be willing to address the calving difficulty issue. Theoretically, the easy calving genetics sought by a dairy farmer, when selecting a bull to mate with the dairy herd, will conflict with those which a beef farmer is looking for in a finishing animal. However, this need not be the case if the dairy farmer is provided with the genetic information now available on all beef-bred bulls recorded with a recognised genetic evaluation data bank. Should an unrecorded bull be used for mating, this could well result in difficult calvings and reduced profit. The dairy farmer will want to target the calving ease EBV (birth weight EBV if this is not available) as his first priority, followed by the gestation length EBV and then either the 200- or 400-day weight EBV, but only if the first two criteria are satisfactory. What sort of beef x dairy animal should the finisher target? They want an animal which they can finish to slaughter at an acceptable weight/grade in as 120 CHAPTER 8 Genetics

18 short a time as possible (maximum months of age). They will therefore be interested in the 400-day weight and carcass weight EBVs, the fat EBVs and possibly the eye muscle area EBV, to ensure adequate carcass muscling. The processor s primary interest is in securing carcasses within a certain weight range, carcass fat levels within a specified depth range and acceptable muscling. Dairy farmers are becoming increasingly aware of the importance of using the right genetics when buying their beef-bred bulls. Some have decided that it is profitable to mate most of their herd to beef-bred bulls and rear the progeny to sell as weaners at 100kg. Herd replacements can be purchased as older cows. By targeting those rare beef-bred bulls with below breed-average birth weight and above average growth rate, the conflict between what traits the dairy farmer and the finisher are interested in is largely removed. Financial benefits to those dairy farmers operating the above system are: Possible cost savings at mating semen cost can be lower than for dairy bred bulls. Improved lactation length if short gestation length bulls are used. A premium on beef x dairy calves compared with straight Friesian or Jersey x Friesian cross calves. This can be substantial, but should be quantified by the dairy farmer. To achieve this result however, it must be recognised that the appropriate beef-bred bulls must be used and that a premium for calves is only achieved when the dairy farmer has developed a reputation for producing calves with good growth genetics. To summarise: Dairy farmers need to be aware of: What genetic information is available in the beef industry, and how to use it to select appropriate bulls that they can trust, in terms of calving difficulty The dangers involved with using beef-bred bulls without EBVs The value of dairy and beef x dairy calves with good growth genetics They need to be encouraged to identify calves and establish the parentage of all calves at birth Rearers must be aware of the existence of growth information (most AI dairy and beef sires have a breeding value for growth) on dairy and beef x dairy calves, and be prepared to pay a premium to dairy farmers for them Finishers also need to be aware of the importance of buying calves with good growth genetics and be prepared to pay a premium for them. CHAPTER 8 Genetics 121

19 Sourcing calves for finishing Traditionally, finishing animals have been sourced from: Selling centres, (saleyards) Directly from producers or growers (private sales) More recently, they have been able to also source them: Through processing companies Via the internet Saleyards are placed strategically in stock catchment areas and animals are transported to the yards and sold by auction. Animals of all ages and sexes are involved from four-day-old calves to mature cattle. In the past, when most stock were driven to the selling centres, there were large numbers of saleyards. Nowadays, animals are being transported longer distances to fewer and fewer yards as rationalisation of the industry takes place. Some of the selling centres now have weighing facilities, where all of the animals are weighed prior to entering the selling arena, and the average liveweights and purchase prices, in dollars/kg liveweight, are displayed. A small number of selling centres are also displaying genetic information, in the form of growth EBVs, at weaner calf fairs. Many finishing animals are sold by private treaty, especially those of dairy origin. Rearers buy four-day-old dairy and beef x dairy calves directly from dairy farmers and either sell these at around 100kg liveweight to finishers or finish the animals themselves. There are some specialist rearers, who rear in excess of 1000 calves annually and on-sell these. A few beef cattle farmers supply selected dairy farmers with beef-bred bulls, with the appropriate genetics, and purchase all or some of the calves from these bulls. This enables them to have control over the genetics of their calves. A recent development has occurred whereby processing companies have formed alliances with bull breeders (who supply either bulls or semen), livestock companies, dairy farmers, rearers and finishers, to achieve continuity of calf supply and greater quality control, from conception to the final beef product. 122 CHAPTER 8 Genetics

20 Further reading Garrick.D.; Villalobos.N.(1999). Genetic Requirements for Intensive Finishing of Beef Cattle. N.Z Beef Council publication BC31, Intensive Beef, Extensive Dollar, P Hogg.B. (1989). The Use of the Carcass Classification System. N.Z. Beef Council publication BC1, Profitable Beef Production Systems, P Kirk.R. (2001). Dairy Beef. N.Z. Beef Council publication BC49, Producing Quality Prime Beef from Dairy Beef Animals, P McCall.D.G. (1989). Profit from Beef Finishing. N.Z. Beef Council publication BC1, Profitable Beef Production Systems, P McCall.D.G. (1992). Efficient Conversion of Pasture to Beef. N.Z. Beef Council publication BC4, Beef Finishing and Marketing, P Morris.S. (1995). Crossbreeding in Beef Cattle Herds. N.Z. Beef Council publication BC9, Beef Breeding Cow Efficiency, P Nicol.A.M. (1999). Principles of Intensive Beef Finishing. N.Z.Beef Council publication BC4, Intensive Beef Production, P Nicol.A.M. (1995). Crossbreeding with Beef Cattle. N.Z. Beef Council publication BC10, Crossbreeding Systems, P Priest.R.G. (2001). Improving Profitability by Sourcing Better Growth Genetics. N.Z. Beef Council publication BC46, Beef Production Field Days, P CHAPTER 8 Genetics 123