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Australian Sheep Breeding Values

Sheep Genetics is the national genetic information and evaluation service for the meat and wool sectors of the sheep industry delivered as LAMBPLAN and MERINOSELECT. The purpose of Sheep Genetics is to improve the quality, scope and utilisation of across-flock, and where appropriate, across-breed genetic information for the Australian sheep industry.

Sheep Genetics provides a single national language for genetic performance in the form of Australian Sheep Breeding Values (ASBVs), which are

  • calculated across-flock and, where appropriate, across-breeds
  • updated following the fortnightly analysis that takes account of all new information supplied by ram breeders
  • reported for a wide range of traits that are relevant to the various sectors of the sheep industry
  • used to compare the genetic potential of animals independent of the environment and location

Australian Sheep Breeding Values are backed by quality assurance procedures and minimum accuracy standards. Sheep Genetics has a database of some three million sheep, from more than 1000 flocks around Australia. ASBVs are an estimate of the genetic potential a sheep will pass on to its progeny. ASBVs are available for a range of economically important traits and are designed to be used in conjunction with visual selection for additional traits relevant to a breeder’s objective.

Sheep Genetics has now released ASBVs for:

  • Early Breech Wrinkle (EBWR), which will assist in the selection of rams that will breed progeny with less wrinkle.
  • Dag (Dag), to assist in the selection of sheep less prone to dag/scouring.
  • Breech cover (BCOV), to assist in selecting sheep with less wool on the breech.

While producers can also select for Worm Egg Count (WEC) to assist in the selection of rams that are resistant to worms, this may not reduce dags. Scouring results from a number of causes, such as high scour worm burdens, hypersensitivity to worm larvae, feed change, enteritis, coccidia and bacteria. To reduce scouring, select for dag independently of worm egg count.

The principals for breeding for lower wrinkle can be applied to breeding for lower breech cover (but depending on your sheep, the response may be lower). If your flock is reasonably wrinkly, concentrate on this first, as wrinkle is easier/faster to change than breech cover. If the flock is already quite plain, then look to improving breech cover and dag.

Using ASBVs allows producers to confidently select sires on the basis of their genes rather than environmental effects. As well as a sheep’s measured or scored performance, ASBVs incorporate information that may not be apparent through visual assessment of rams at the time of selection. This includes pedigree information and the effects of sex, birth type and dam age that can all mask the performance of a ram’s progeny.

For example:

  • A lamb born as a twin is likely to be 0.3–0.5 score plainer than a lamb born as a single in the same environment
  • A lamb born on poor feed is likely to be 0.5–1.0 score plainer than a lamb born on good feed
  • A lamb born from a maiden ewe is likely to be 0.1–0.2 score plainer than a lamb born to a mature ewe

ASBVs remove these effects and allow sheep to be compared on their genetic merit.

For more information about ASBVs visit the Sheep Genetics website.

Early Breech Wrinkle Breeding Values

Breech wrinkle breeding values (EBWR) have been developed because the trait has a large impact on breech strike risk and is both cheap and easy to score. Wrinkle ASBVs have been developed using published research on the genetics of skin wrinkle, as well as breech and body wrinkle score data collected from MERINOSELECT member flocks, Central Test Sire Evaluation sites, the Sheep CRC Information Nucleus Flocks and the AWI breech strike research flocks. The result is highly accurate genetic parameters and a good understanding of the impact of non-genetic effects on expression of the trait.

Both breech and body wrinkle have an estimated heritability of 0.35, which is similar to body weight, staple strength and eye muscle depth. There is an unfavourable relationship between breech wrinkle and fleece weight (low wrinkle score sheep tend to have slightly lower fleece weights) however the antagonism between these traits is small and less than the antagonism between fibre diameter and fleece weight.

Industry experience has shown it is possible to breed sheep with reduced fibre diameter and increased fleece weight, despite the antagonistic relationship between these traits. The same is true for wrinkle score and fleece weight – therefore it is possible to breed plainer sheep and improve fleece weight at the same time. As with all traits, it is important to keep selection for wrinkle in balance with other traits in your breeding objective.

Download the Early Breech Wrinkle ASBVs document below.

Download Early_Breech_Wrinkle_ASBVs_130410.pdf (165 KB)

ASBVs are expressed as a positive or negative deviation from an average in the database. The current trait leaders for Early Breech Wrinkle are -1.0 to -1.7 score plainer than the average sires in the MERINOSELECT database. For trait leaders reports click here.

Worm Egg Count Breeding Values

Sheep with more negative Worm Egg Count (WEC) ASBVs produce progeny with higher resistance to worm burdens. Sires with low Worm Egg Count (WEC) ASBVs may assist in reducing the incidence of dag and flystrike risk in certain environments. Current MERINOSELECT trait leaders for yearling WEC have -100 to –98% ASBVs.

New Breeding Values under Development

ASBVs for dag score (LDAG) and breech cover (EBCOV) have also been developed. In areas where dag is a major risk factor, the ability to select for low dag score will increase the breeder’s ability to select sheep with lower flystrike susceptibility. For animals with low wrinkle score, selection for low breech cover can further reduce flystrike susceptibility.

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