Associations between Gene Polymorphisms, Breeding Values, and Glucose Tolerance Test Parameters in German Holstein Sires

The association between several gene polymorphisms, the estimated breeding values for milk performance traits, and glucose metabolism measured by the glucose tolerance test (GTT) in German Holstein sires were evaluated. Polymorphisms in DGAT1, GH1, GHR, FASN, and OLR1 genes were not associated with the GTT. A significant relationship was obtained for the DGAT1 AA/GC polymorphism and estimated breeding values for milk performance (milk yield, fat and protein yield, fat and protein percentage). The polymorphism in GHR was significantly associated with estimated breeding values for fat yield, and the polymorphism in OLR1 with estimated breeding value for protein yield. It shows the importance of the polymorphisms and makes their use in the breeding possible. GTT may be helpful in metabolic analyses, but the gene polymorphisms assessed in our study were not associated with GTT traits and further studies should examine other gene polymorphisms to support the role of GTT for potential breeding purposes.