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Developing Multi-breed Breeding Values for Beef Cattle

Mick Deland, Struan Research Centre, SARDI
John Graham and Allan Clark, PVI Hamilton, Agriculture Victoria, ph 03 5573 0900.

Vision: 'To be able to compare and select any bull, regardless of breed to produce exactly what you want'

Regional Combinations Project

Because of the increasing demand for quality assurance practices in the beef industry, the National Beef Improvement Association Council decided that Multi-breed Estimated Breeding Values (EBVs) could significantly improve returns from beef production by improving the ability of producers to market cattle with predictable performance.

It is important to be able to describe differences between animals to be used in a breeding program. The accurate description of the genetic merit of bulls and cows within and across breeds and crosses, will increase the effectiveness of both pure-breeding and cross-breeding programs.

Same age, same feed, different genetics, different yield

Why is there a need to develop across-breed EBVs?

The current EBVs from GROUP-BREEDPLAN will allow you to choose the most suitable sires with the traits required from within a breed, however, you cannot compare the EBVs of sires from different breeds.

Regardless of which EBVs are available, the choice of which sire to use to produce specific characteristics is not easy. Not only do you have to consider the use of sires to produce progeny for slaughter but, in a self replacing herd, you also have to consider the breeding of replacement heifers, and the desirable dam traits. The importance of being able to gain as much information as possible about the stock used for breeding cannot be stressed highly enough because of the severe penalties for cattle which do not meet market specifications or, conversely, the premiums for desirable types. Contracts are now available for desired types for several different markets.

The use of Multi-breed EBVs will assist with those important decisions.

The Meat Research Corporation, in conjunction with Agriculture Victoria and the South Australian Research and Development Institute of South Australia, are funding a project examining the development of Across Breed Estimated Breeding Values (Multi-breed EBVs).

The project aims, by 2002, to have Multi-breed EBVs available for beef sires in Australia. Put simply, the long term vision is: 'To be able to compare and select any bull regardless of breed to produce exactly what you want.'

To develop Multi-breed EBVs, it is necessary to:

1. Obtain good links between the breeds and calculate heterosis estimates for some of the breed crosses.
2. Examine whether a bull's purebred progeny will rank the same as his cross-bred progeny.
3. Estimate differences between breeds in fertility, maternal traits and production.

Two existing projects in Australia can assist with goal 2 (above). Some common sires are being used which will allow the information from the projects to be combined.

The existing projects are the Southern Crossbreeding Project, a joint project between the SA Cattle Compensation Fund, the University of Adelaide and SARDI and the CRC for Meat Quality (beef cattle) Tropical Cross-Breeding Program. Table 2 shows the dam breeds and sire breeds used in these projects.

 Table 2: Dam and Sire breeds used in two major crossbreeding projects

The new MRC funded project will:

1. Provide linkages between the breeds, which allow baseline estimates of breed genetic values to be calculated
2. Provide links between the two projects above, so that data from all three programs can be used to estimate the initial genetic correlation between purebred and cross bred performance by the staff of Animal Genetics and Breeding Unit (AGBU), Armidale
3. Examine the ranking of high EBV beef sires from at least four sire breeds over at least two dam breeds
4. Investigate fertility, maternal traits and reproductive performance.

Angus, Hereford, Limousin and Simmental are the four sire breeds being used in this project. Angus and Hereford are the two major breeds in southern Australia, based on herd registrations followed by Limousin and Simmental. These four sire breeds provide diverse genotypes, with two representing the most common British breed cattle type, and two representing European-type cattle.

To examine the ranking of sires of different breeds, bulls used in this project need to have high accuracy EBVs, and represent a range of sire performance within the breed.

Six hundred cows for this project were run at Struan Research Centre with a further 300 at the Pastoral and Veterinary Institute. The remaining cattle required were sourced from private properties.

The dam breeds were Angus and Hereford. Mating was done using synchronised AI, giving each cow two opportunities to conceive. Independent AI technicians conducted the matings on cooperating properties.

At weaning all steer and some heifer progeny were purchased and backgrounded on a common property, decreasing the variation in the herd as a whole. This helped with marketing arrangements, and minimised the effect of pre-weaning management on the animals. They were then grown out in either pastures or feedlots to 2 different slaughter weights: 270 kg cwt for the Korean market or 320 kg cwt for the Japanese market.

During the finishing phase, the animals were scanned regularly for eye muscle area and p8 fat depth. By collecting regular scan information and having two slaughter weights, it will be possible to construct growth curves for the breeds/ genotypes, allowing interpolation to alternative slaughter weights and end-points.

The list of traits recorded on the cattle are shown below. All traits are available for inclusion in Breedplan. These traits include those available now and those likely to be available in the future (such as direct carcass measurements).

Measurements taken:

• Calving ease, Milk production
• Fertility - Days to calving, Pelvic size
• Birthweight Carcass Weight, Dressing Percentage
• Cannon-bone length at birth AUS-MEAT Chiller Assessment
• Liveweight at weaning P8 fat - carcass, Eye Muscle Area
• Condition score at weaning 12/13 fat depth - Carcass
• P8 fat - ultrasound, at weaning Chemical fat
• Liveweight 200, 400, 600 days
• P8 fat - live 400, 600 days Additional Measurements
• 12/13 fat depth
• Marbling Blood Samples for DNA testing
• Meat samples for fatty acid analysis, melting point

Heifers were retained at the research stations in order to examine breed differences between days from joining to calving; age of puberty; post-calving anoestrus interval; milk production and pelvic size.

Widespread use of crossbreeding in Australia will lead to a large supply of F1 females. Their use as potential replacements for the herd needs to be considered, and measures of fertility need to be made to achieve this.

This project offers a unique opportunity to study causes of variation in reproduction, growth and carcass, from conception to consumption. ie, the complete production and market chain. This will assist with an audit of wastage and opportunities for improvement of the total system. It involves purchase and transport of stock, marketing, feedlotting and processing/distribution of meat. A summary of results to date follows:

Spring and autumn calving Angus and Hereford cows were impregnated with semen from 88 Angus, Hereford, Limousin and Simmental sires in 1997 and 1998. Progeny from Angus cows were significantly heavier (P<0.05) and fatter than those from Hereford cows (282.9 and 265.6kg and 4.1 and 3.3mm, respectively). Sire breed also significantly effected weaning weight and fatness, being 282.9 and 4.2, 267.d and 4.4, 275.6 and 3.2, and 284.6 kg and 3.1 mm respectively. Eye-muscle area of 549 autumn born weaners at 455 days using ultrasound, was significantly effected (P<0.05) by dam breed (Angus 50.9, Hereford 49.2 cm²) and sex (Heifers 50.8 and Steers 49.3 cm²). The project is being funded by the MLA, NRE Vic. And SARDI, SA and evaluation of carcasses and meat samples will be conducted over the next 12 months prior to the full EBV evaluation.

The following areas can be examined using this cattle herd:

• Effect of breed genotype on alternative finishing systems
• Genetic variation for meat quality and disease resistance traits (including the existing variation for trace element levels)
• Genetic variation for factors affecting dark cutting and shelf-life in beef e.g. muscle enzyme activity. Discussions have been held with Dr Robyn Warner, VIAS, Werribee, regarding collaboration between groups working on the MRC-funded dark cutting project and this project.
• Prediction systems for meat quality analysis. For example, the cattle will show larger than normal variation for many traits of economic importance, such as muscularity. The herd then could become a resource for predictions of meat quality using live animals and visual or ultrasound techniques.
• Economics of crossbreeding systems. We have already had expressions of interest from universities wanting interactive computer-based teaching programs which can predict economic outcomes from a variety of senarios. Basic data from our program will facilitate this.
• The herd will be a resource for DNA marker studies, in particular, where markers have been identified and need to be validated in the wider population.
• The nature of this cattle herd makes it a good source of cattle for the MRC - funded store link and meat quality projects.
• The herd is being used in the MRC-funded National Identification Project, with cows and calves identified with a variety of devices, some of which will be recovered at slaughter.

All the AI costs, including semen and cattle tags, are being provided to cooperating producers. Cooperating producers will also receive regular reports on the performance of their cattle from birth to slaughter, and at weaning will receive a bonus of $30/calf weaned from the AI program. The herd will be fully performance-recorded. Those producers providing semen to the project will receive regular reports on the performance of their bulls.

Mating commenced in June 1997 when 1361 cows of either Hereford or Angus breeding were inseminated.