Sheep Industry News August 2023

The Potential Value of International Sheep Evaluations

ANDREW HESS, LUIZ BRITO & TOM MURPHY I n the United States, the five breeds with the greatest num ber of National Sheep Improvement Program records are Katahdin, Polypay, Targhee, Rambouillet and Suffolk. Many of these breeds – or derivatives thereof – are also found in the top sheep-producing regions of the world such as Aus tralia, New Zealand, France and the United Kingdom. In these countries, the use of genomics has become com monplace, with genomic information being an integral part of national genetic evaluations. Integration of genomics has had a desirable impact on sheep production and welfare in

of this approach depends on the sharing of breeding ani mals (in the context of dairy cattle, bulls and semen) across these countries, which allows the information to be captured through shared pedigree relationships between the countries. In this way, the countries become linked by shared genetics. Through international evaluations, animals can be more reliably compared throughout the world in the context of a given country of interest. International evaluations and inter national trade of semen also has the opportunity to increase genetic diversity through introduction of new genetic lines. An increase in the level of inbreeding is a natural conse quence of genetic selection, because genetically more simi lar individuals are expected to rank more similarly in their performance than with phenotypic selection.

these countries, with an increase in the rate of progress being observed, particularly for expensive- and hard-to-measure traits, such as feed efficiency and meat quality. This increase in the rate of genetic progress can in part be attributed to more accurately capturing the relationships between indi viduals, particularly across breeds where relationships are not captured using pedi gree information. This typically results in an improvement in the ability to estimate the genetic merit of an individual, particularly at a younger age. Genomic selection is a numbers game, and the accuracy of selecting the best animals improves as the number of ani mals with both genotypes and phenotypes gets larger. In these top sheep producing

It has been observed in species such as dairy cattle – which were early adopters of genomic selection – that rates of in breeding per year have accelerated since the implementation of genomics selection due to the ability to select superior ani mals more intensely and accurately at a younger age. Obvi ously, the benefits have outweighed the consequences to date, with substantial genetic improvement being made in both the dairy and international sheep industries. Genetic evaluations that incorporate genomic information have become commonplace in the global dairy cattle indus try, which has been greatly facilitated by early and strong adoption of the genotyping technologies in the industry, and this information has also been integrated into these genetic

countries that have embraced genomic selection, a wealth of genomic and phenotypic information is being collected. For example, a report generated for the Australian sheep industry states that more than 120,000 sheep had been genotyped for genomic selection in the 2021-2022 year alone. The countries that have amassed a wealth of data have the potential to setup international genomic evaluations for selection of animals with superior performance across a range of environments. A prime example of the potential that can be tapped when considering international genetic evaluations can be found in the dairy cattle industry through the efforts of Interbull, which implemented the first international evaluation (mul tiple across-country evaluations) in the 1980s. The success

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