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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 #327544

Title: Breed base representation in dairy animals of 5 breeds

item NORMAN, H - Council On Dairy Cattle Breeding
item Vanraden, Paul
item MEGONIGAL, JOEL - Council On Dairy Cattle Breeding
item DURR, JOAO - Council On Dairy Cattle Breeding
item COOPER, TABATHA - Former ARS Employee

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/2016
Publication Date: 7/9/2016
Citation: Norman, H.D., Van Raden, P.M., Megonigal, J.H., Durr, J.W., Cooper, T.A. 2016. Breed base representation in dairy animals of 5 breeds. Journal of Dairy Science. 99(E-Suppl. 1)/Journal of Animal Science. 94(E-Suppl. 5):151-152(abstr. 0324).

Interpretive Summary:

Technical Abstract: Inheritance of DNA from different dairy breeds can be determined by genotyping, just as individual ancestors such as parents, grandparents, or even great grandparents can be identified correctly in a high percentage of the cases by genotyping even if not reported or reported incorrectly in pedigrees. Numbers of crossbreds in the US dairy herd have increased by about 400% in the last decade. A procedure developed to determine the extent that alleles of various breeds appear represented in these crossbreds and in apparent purebreds was used to document breed composition in animals genotyped. The procedure constructed purebred reference groups (PRG) containing registered AI bulls (with milking daughters) chosen to represent 5 different breeds: Ayrshire (AY), Brown Swiss (BS), Guernsey (GU), Holstein (HO), and Jersey (JE). Any bulls having an ancestor of another breed in his recorded 5-generation pedigree was excluded from the PRG. An exception was made for AY where other red breeds were permitted. The procedure was termed Breed Base Representation (BBR) and estimated the similarity of the alleles present in the 5 PRGs to those of individuals genotyped. BBR percentages of the 5 breed alleles were calculated, then restricted to be between 0 and 100% for each genotyped animal, and summed. The more an animal’s alleles resembled those in a PRG, the higher its BBR percentage for that breed. The percentages help reveal the presence of either outcross bloodlines or crossbreeding, which are difficult to separate. Because animals vary even within breeds, the true source of the various breed alleles differs somewhat from the BBR percentages derived by the procedure. The number of AI bulls in the reference populations in March 2016 were 442 AY, 5,464 BS, 550 GU, 19,209 HO and 3,147 JE. The percentage of the primary breed for these were 97.2, 97.6, 97.8, 99.2, and 98.0%, respectively, implying they are indeed purebreds. The standard deviations (SD) were 1.9, 1.2, 2.7, 1.2, and 1.0%. The mean percentages were 94.8, 97.0, 97.8, 99.0, and 96.5%, respectively for all males genotyped for these breeds (201,283), and 95.0, 97.1, 96.9, 98.9, and 96.5% for all genotyped females (994,949). SDs for all males and females genotyped ranged from 1.2 and 1.5% (HO) to 5.6 and 4.4% (AY). Genetic predictions for animals having crossbred genetics in their pedigrees could be obtained in the future by weighting marker effects from each breed by BBR.