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Title: CHARACTERIZATION OF DGAT1 ALLELIC EFFECTS IN A SAMPLE OF NORTH AMERICAN HOLSTEIN CATTLE.

Author
item BARBOSA DA SILVA, M - Embrapa
item Sonstegard, Tad
item Thallman, Richard - Mark
item Connor, Erin
item SCHNABEL, ROBERT - UNIVERSITY OF MISSOURI
item Van Tassell, Curtis - Curt

Submitted to: Animal Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2009
Publication Date: 4/20/2010
Citation: Barbosa Da Silva, M.V., Sonstegard, T.S., Thallman, R.M., Connor, E.E., Schnabel, R.D., Van Tassell, C.P. 2010. CHARACTERIZATION OF DGAT1 ALLELIC EFFECTS IN A SAMPLE OF NORTH AMERICAN HOLSTEIN CATTLE. Animal Biotechnology. 21(2):88-99.

Interpretive Summary: Traditional methods of genetic selection have greatly improved milk production traits, but genomic tools could enhance this improvement. The first verified genetic test in dairy cattle was identified recently as DGAT1, a gene effecting fat synthesis. The genetic differences at this gene were characterized in North American Holstein and Jersey populations for the first time. Statistically significant effects were identified for all of the milk production traits and udder healrh (SCS). Estimated differences for bull evaluations were -81 kg, 3.7 kg, -1.1 kg, 0.63%, 0.12%, and -0.23 units for milk yield, fat yield, protein yield, fat component, protein component, and SCS when one copy of the alternate form is substituted for the other. These estimates agree in directions with results from prior studies, but the magnitude is much smaller in this study. Impacts on economic indices were modest at $2 to $18 depending on the assumed market. Because of the strong antagonism of fat and protein yield and that influence on economic indices, selection for DGAT1 genotypes will likely not find widespread application in North America.

Technical Abstract: A number of quantitative trait locus studies had identified regions on the centromeric end of bovine chromosome 14 prior to the identification of the putative causative mutation as a lysine to alanine substitution at amino acid 232 of the protein coded by the acylCoA:diacylglycerol acyltransferase (DGAT1) gene. The goal of this project was to characterize the mutation in a large sample of North American Holstein bulls. A secondary goal was to characterize the effects on the Jersey breed. Statistically significant effects were identified for all of the milk production traits and SCS. Estimated average effects of allele substitutions on bull daughter yield deviations were -81 kg, 3.7 kg, -1.1 kg, 0.63%, 0.12%, and -0.23 units for milk yield, fat yield, protein yield, fat component, protein component, and SCS for substituting the lysine allele for an alanine allele. These estimates agree in directions with results from prior studies, but the magnitude is much smaller in this study. Impacts on economic indices were modest at $12.18, $17.60, and $2.12 for net merit, cheese merit, and fluid merit. Possible explanations for the differences in effect estimates include importation of North American germplasm in previous studies, genotype-environment interaction, and influence of other DGAT1 mutations on the estimates. Because of the strong antagonism of fat and protein yield and that influence on economic indices, selection for DGAT1 genotypes will likely not find widespread application in North America.