Effect of the DGATI gene polymorphism on milk production traits in Black-and-White (Friesian) cows.

The effect was studied of the lysine/alanine (K232A) diallelic polymorphism in acylCoA-diacylglycerol-acyltransferase 1 (DGAT1) on milk production traits in a sample of Polish-Black-and-White (Friesian) cows. The considered polymorphism results from AA→GC nucleotide substitution in DGAT1 gene exon 8. Genotyped were 177 cows out of which 86 were included in the association study. The DGAT1 genotype showed no significant effect on the daily milk yield. Moreover, no differences were found between genotypes in daily yield of fat-corrected-milk (FCM) and mean daily value-corrected milk (VCM). The cows of DGAT1 genotype AA/GC yielded milk with significantly higher fat and total protein content than those of GC/GC genotype. Moreover, the AA/GC cows produced milk with higher total solids and solids-non-fat content. The total milk protein to milk fat ratio in AA/GC cows was 0.79, while 0.83 in GC/GC cows. No significant differences were found between genotypes in the weight of milk components produced daily. The study showed some associations occurring between genetic variants at the coding region of the bovine DGAT1 gene and milk production traits of Polish Blackand-White (Friesian) cattle; in particular the AA allele (coding for lysine) appeared favourable for fat and protein content of milk.