Effects of DGAT1 variants on milk production traits in Jersey cattle

The aim of the study was to analyse the K232A polymorphism in the acyl CoA:diacylglycerol acyl-transferase gene (DGAT1) and to estimate the effects of lysine (K) and alanine (A) encoding variants on milk yield and composition in cattle. A total of 100 Jersey cows was tested for DGAT1 genotypes using the PCR-RFLP technique. The K and A allele frequencies were 0.83 and 0.17, respectively. Effect of the K232A polymorphism on most considered traits was observed. The lysine encoding variant was associated with the high milk fat yield as well as fat and protein contents, whereas the alanine allele was related to the increased milk yield. The most significant result was obtained for the fat content of milk. None of the dominance effects proved to be significantly different from zero, that indicates the additive effect of the gene. KEY WORDS: cattle / DGAT1 / milk traits / polymorphism Fat is one of the major components of milk and is a key source of energy to the suckling young mammals. Milk fat is primarily composed of triglycerides (triacylg-lycerols or TAG), a typical storage form of lipids, which account for over 95 % of the total milk fat [Jensen 2002 – a review]. One of the key enzymes in triglyceride metabolism is acyl CoA:diacylglycerol acyltransferase (DGAT), an integral microsomal membrane enzyme that catalyse