Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/4/2014
Publication Date: 6/1/2014
Publication URL: http://handle.nal.usda.gov/10113/58869
Citation: Cooper, T.A., Wiggans, G.R., Null, D.J., Hutchison, J.L., Cole, J.B. 2014. Genomic evaluation, breed identification, and discovery of a haplotype affecting fertility for Ayrshire dairy cattle. Journal of Dairy Science. 97(6):3878-3882. Interpretive Summary: Genomic selection of dairy cattle in the U.S. to improve health and profitability has been used in the Holstein, Jersey and Brown Swiss breeds since 2009. This research investigated if genomic evaluation of a smaller breed, Ayrshire, was justified. The increase in reliability of using genomic evaluations over traditional ones was found to be 8.2 points when averaged across 23 economically important traits. In addition to providing a more accurate ranking to increasing profitability of this breed, a haplotype affecting fertility was discovered on chromosome 17.Over a quarter of the population was found to be carriers of the deleterious haplotype, which lowered conception rate by 4.4%. Consideration of this haplotype in mating programs can increase fertility.
Technical Abstract: Genomic evaluations of dairy cattle in the US have been available for Brown Swiss, Holstein and Brown Swiss since 2009. As of February 2013, there were 1,100 genotyped Ayrshires in the North American database, including 646 bulls with traditional evaluations, permitting the investigation and implementation of genomic evaluation for this breed. The average gain in reliability over parent average for all traits was 8.2. The highest gains were found in milk yield (16.6), protein yield (16.9) and stature (16.2). There are 12 single nucleotide polymorphisms (SNP) in Ayrshire that can be used for breed determination. There are fewer breed-determining SNP in Ayrshire than in Holstein, Jersey and Brown Swiss, due to the similarity of Ayrshire and Holstein. A haplotype affecting fertility was identified on chromosome 17, and originated in the genotyped population with SELWOOD BETTY'S COMMANDER (b. 1953). The carrier frequency for genotyped Ayrshires is 26.1%. Sire conception rate was 4.4 ± 2.5% lower for carriers of the haplotype as determined by 483 carrier sire-by-maternal grandsire carrier matings.