Abstract #63

# 63
The effect of genomic selection on dairy cow populations.
J. E. Pryce*1,2, 1Agriculture Victoria, Bundoora, VIC, Australia, 2La Trobe University, Bundoora, VIC, Australia.

Genomic information has been used routinely in national genetic evaluations worldwide since 2008. Now, close to a decade later, what are the impacts on dairy populations? In 2011 the reliabilities of genomic breeding values for total merit indices for various surveyed countries were around 60%, the reliabilities have increased by about 10 points as a result of increasing the size of reference populations and improvements in methodology. As genomic selection has become an accepted technology, the majority of dairy inseminations are to young genomic bulls without daughters. Doubling of the rate of genetic gain (compared with before the implementation of genomics) is common and comparable to predictions in the era before implementation. At the same time, rates of inbreeding also appear to have doubled. Paradoxically, the number of carriers of known lethal recessives has been reducing, presumably because carrier sires are being avoided. However, higher rates of inbreeding under genomic selection means that new methods of control at a population, breeding company and herd level are becoming increasingly important. In addition to increasing rates of genetic gain by identifying the best cows to keep and breed from and controlling inbreeding through genomic mating plans, farmers genotype their cows for several reasons. For example, there are opportunities to sell elite youngstock at a premium and achieve certainty of parentage. There are also opportunities to select for desirable alleles, such as genotyping for the β casein variant known as A2. This has become popular in Australia as the market share for milk produced by cows that are homozygous for A2 increases. The availability of high genetic merit homozygous polled bulls has also increased, which enables breeders to breed solely polled replacements. Genomic breeding values are becoming available for hard-to-measure traits such as feed efficiency, methane emissions and heat tolerance, which would not be possible without genomics. The result is that genomics is being used for accelerated rates of genetic gain and improved management decisions.

Key Words: genetic gain, genomics

Speaker Bio
Dr Jennie Pryce is Principal Research Scientist of Agriculture Victoria and La Trobe University, located at AgriBio, where she leads a large team of scientists and supervises PhD students. Her main areas of interest are genetic improvement of functional traits in dairy cattle, optimising breeding scheme design under genomic selection and development of dairy selection indices.
Jennie is also a senior editor with the Journal of Dairy Science and a member of the ICAR (International Committee on Animal Recording) working group on functional traits. In Australia, Jennie is Lead Scientist of DataGene and also sits on several industry and research alignment groups that shape the future of dairy research in Australia.