GH and CSN3 gene polymorphisms and their impact on milk traits in cattle

Abstract

Associations of milk production traits with growth hormone (L/V) and κ-casein (A/B) gene polymorphisms were investigated in this study. Official breeding values of genotyped 99 AI bulls for milk, protein, fat yields as well as fat and protein contents were used to study genotype effects on the production traits. Effects of four single-locus genotypes (LL, LV, AA and AB) and four two-loci genotypes (AALL, AALV, ABLL and ABLV) were estimated. The AB genotype showed an advantage over the AA homozygote in terms of fat and protein contents. No significant relationships between the GH polymorphism and the breeding values were found. The analysis of the effect of two-loci genotype reflected the relationships observed for single-locus analysis and ABLL and ABLV genotypes were related to higher breeding values for fat (ABLV) and protein (ABLV and ABLL) contents. The contradictory effects of the studied genetic variants are discussed.