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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Genomics and Improvement Laboratory » Research » Publications at this Location » Publication #321362
Title: Genomic evaluation, breed identification, and population structure of Guernsey cattle in North America, Great Britain, and the Isle of Guernsey

Author
item Cooper, Tabatha
item EAGLEN, SOPHIE - Roslin Institute
item Wiggans, George
item JENKO, JANEZ - Roslin Institute
item HUSON, HEATHER - Cornell University
item MORRICE, DAVID - University Of Edinburgh
item BICHARD, MAURICE - Collaborator
item DE L. LUFF, W. - Collaborator
item WOOLLIAMS, JOHN - Roslin Institute

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2016
Publication Date: 7/1/2016
Citation: Cooper, T.A., Eaglen, S.A., Wiggans, G.R., Jenko, J., Huson, H.J., Morrice, D.M., Bichard, M., De L. Luff, W.G., Woolliams, J.A. 2016. Genomic evaluation, breed identification, and population structure of Guernsey cattle in North America, Great Britain, and the Isle of Guernsey. Journal of Dairy Science. 99(7):5508-5515.

Interpretive Summary: Genomic evaluations have been available for US Holsteins, Jerseys, and Brown Swiss since 2009 and for Ayrshire since 2013. As of January 2015, 2,263 Guernsey bulls and cows had genotypes from collaboration between the United States, Canada, England, and the Isle of Guernsey. The mean gain in reliability for genomic evaluations over parent averages for all traits was 14.4 percentage points. Principle component analysis shows some divergence of USA and Guernsey Island populations. However, the overlap of populations indicates the presence of gene flow and the similarity in the sub-populations supports a common genomic evaluation system across the regions.

Technical Abstract: Genomic evaluations of dairy cattle in the United States have been available for Brown Swiss, Holsteins, and Jerseys since 2009 and for Ayrshire since 2013. As of January 2015, 2,263 Guernsey bulls and cows had genotypes from collaboration between the United States, Canada, England and the Isle of Guernsey. Of those, 353 were males with traditional evaluations. Evaluation accuracy was assessed using a cross-validation study where 25 percent of males were randomly assigned to the validation group and the remaining males were assigned to the training set. This was repeated ten times and gains in reliability over parent average were averaged across runs. Twenty-two traits were analyzed including five yield traits, three functional traits and fourteen conformation traits. Mean gain in reliability over parent average for all traits was 14.4 percentage points. The highest gains were for strength (25.1), rump width (24.8), fat percent (24.2), and stature (24.0). Traits with the lowest gains were somatic cell score (0.9) and protein yield (1.0). The gains for Guernsey can be compared with average gains of 9, 24, 40, and 31 for Ayrshire, Brown Swiss, Holstein and Jersey respectively. Twenty single nucleotide polymorphisms were identified for Guernsey breed determination and are used in routine genotype quality control to confirm breed and identify crossbreds. No haplotypes that affect fertility were identified from the current data set. Principle component analysis shows some divergence of USA and Island Guernsey populations. However, the overlap of populations indicates the presence of gene flow and the similarity in the sub-populations supports a common genomic evaluation system across the regions.