Effect of DGAT1 gene variants on milk quantity and quality in Holstein, Simmental and Brown Swiss cattle breeds in Croatia

Abstract

The aim of this study was to determine allele frequency at the diacylglycerol-O-transferase 1 gene (DGAT1) K232A polymorphic site and effect of allelic variants K and A on milk production traits of Holstein (dairy), Simmental and Brown Swiss (dual purpose) cattle breeds in Croatia. The DNA was extracted from hair of 371 cows, while coding region of DGAT1p.K232A was amplified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Dominant frequency of K allele was determined in all three analysed breeds: Holstein (0.775), Simmental (0.616) and Brown Swiss (0.651). The most Holstein cows were homozygotus for KK variant (0.637), while dominant genotype in other two breeds was KA (Simmental 0.647; Brown Swiss 0.644). Positive effect of KK genotype on milk yield was detected in Holstein and Brown Swiss breeds, while in Simmental breed was negative (-220.8 kg; -463.6 kg) in regard to KA and AA genotype. Milk of cows with KK genotype in Holstein breed, KA in Simmental and AA in Brown Swiss were found as the most favourable in terms of fat content. Cows of AA genotype in all the three analysed breeds have had higher milk protein content. Statistical analysis was performed using the GLM procedure, including genotype and breed effects as independent variables. The effects of DGAT1genotypes on milk quantity and quality were not significant (P>0.05).

Keywords

• cattle
• DGAT1
• polymorphism
• production traits
• milk