Genetic Variation of DGAT1 Gene and its Association with Milk Production in ranian Holstein Cattle Breed

. The results of multiple QTL mapping design in recent years indicated quantitative trait loci for milk fat percentage and milk yield traits identified in BTA14. DGAT1 gene coding diacylglycerol-acyltransferase enzyme, has a main role in the triglyceride synthesis and finally fat milk synthesis. A transition mutation in this gene results substitution of guanine by adenine in the gene causing substitution of lysine by alanine in diacylglycerol-acyltransferase enzyme. In this research, 398 blood samples were collected from the farms Tehran and Esfahan provinces. Using PCR reaction, 411 bp fragment of exon 8 DGAT1 gene was amplified. Finally, genotyping of the population was performed using RFLP- PCR technique. Three genotypes were detected. KK individuals with no mutant allele, AA individuals with two mutant alleles and KA individuals with one mutant allele. 36, 226 and 136 individuals had KK,KA and AA genotypes, respectively. Frequencies of DGAT1 alleles (K and A) were estimated 0.37 and 0.63, respectively. The effect of DGAT1 gene on milk305 trait was significant (P=0.001).