The relation of GH1, GHR and DGAT1 polymorphisms with estimated breeding values for milk production traits of German Holstein sires

Abstract

: We analysed the relations of estimated breeding values (EBV) of 315 German Holstein sires to their genotypes in growth hormone gene (<i>GH1</i>), growth hormone receptor gene (<i>GHR</i>) and acylCoA-diacylglycerol acyltransferase 1 (<i>DGAT1</i>). The strong relation of <i>DGAT1 K232A</i> to the estimated breeding values for milk production traits has been confirmed, when allele <i>DGAT1^K</i> was connected with higher milk fat yield, milk fat and milk protein content, while allele <i>DGAT1^A</i> increased milk yield and milk protein yield. The effect of <i>DGAT1</i> genotype explained from 4.70% of variability of EBVs for fat yield to 31.90% of variability of EBVs for fat content. The evaluation of <i>GH1</i> 127 Leu/Val and <i>GHR</i> 257 SNP polymorphisms did not reveal an association of their polymorphism with EBVs for milk production traits, except the EBVs of <i>GHR^G/GHR^G</i> homozygotes for fat yield, which were significantly lower. The effect of <i>GH1</i> or <i>GHR genotype explained only a negligible portion of variability of EBVs (<i>R</i>² < 1.00% in most cases).