Abstract #T88

# T88
Genomic evaluation, breed identification, and population structure of North American, English and Island Guernsey dairy cattle.
Tabatha A. Cooper*1, Sophie A. E. Eaglen2, George R. Wiggans1, Janez Jenko2, Heather J. Huson3, David M. Morrice2, Maurice Bichard4, William G. Luff5, John A. Woolliams2, Brian P. Van Doormaal7, 1Animal Genomic and Improvement Laboratory, Agricultural Research Service, USDA, Beltsville, MD, 2The Roslin Institute & R(D)SVS, University of Edinburgh, Easter Bush, United Kingdom, 3Department of Animal Science, Cornell University, Ithaca, NY, 4English Guernsey Cattle Society, Launceston, United Kingdom, 5World Guernsey Cattle Federation, Castel, Guernsey, United Kingdom, 6Select Sires, Plain City, OH, 7Canadian Dairy Network, Guelph, ON, Canada.

Genomic evaluations of dairy cattle in the United States have been available for Brown Swiss, Holstein, and Jersey since 2009 and for Ayrshire since 2013. As of February 2015, 2,281 Guernsey bulls and cows had genotypes from collaboration between the United States (USA), Canada (CAN), England (E), and the Island of Guernsey (I). The E /I contributions were made possible by the European Commission project, Gene2Farm. Of those genotyped, 431 were males with traditional evaluations. Evaluation accuracy was assessed using 4-fold cross-validation using males only. The cross-validation was repeated 10-fold and gains in reliability over parent average were averaged. Twenty-two traits were analyzed including 5 yield traits, 3 functional traits and 14 conformation traits. Mean gain in reliability over parent average for all traits was 13.8 percentage points. The highest gains were for strength (26.7), rump width (23.6), fore udder attachment (23.2) and fat percent (21.1). Traits with the lowest gains were daughter pregnancy rate (1.0) and somatic cell score (−0.9). The average 13.8-point gain for Guernsey can be compared with averages of 9, 24, 40, and 31 for Ayrshire, Brown Swiss, Holstein, and Jersey respectively. Twenty-one single nucleotide polymorphisms were useful for Guernsey breed determination and are used in routine genotype quality control to confirm breed and identify crossbreds. Genetic differences between E/I animals and USA/CAN animals from an admixture study using principal component analysis will be presented. No haplotypes that affect fertility were identified from the current data set however; monthly assessments are conducted. These results are expected to lead to routine genomic evaluation of Guernseys in the USA and E/I.

Key Words: Guernsey, genomic evaluation, single nucleotide polymorphism