polymorphisms of pou1f1 and stat5a genes and their associate on with milk production traits in cattle

specific trait candidate genes are sequenced genes with known biological activity. the effects of pou1f1 and stat5a on milk production traits have been studied in several studies. pou1f1 affects on transcription of prolactin and growth hormone gene, as well as, stat5a is known as a main mediator of growth hormone action on target genes and intracellular mediator of prolactin signaling. since these genes are essential for development of mammary system, the aim of this study was to determine association of their polymorphism with milk production breeding values in brown swiss cattle. blood of ninety milking cow were randomly obtained. dna was extracted from whole blood using modified salting out method, then the desired fragments were pcr amplified and digested by specific restriction endonuclease enzymes. gene and genotype frequencies, heterozygosity indexes, the real and effective allele number were calculated by popgene software; and the breeding values of production traits were estimated by dfreml. sas software was used to analyze association between genotypes and breeding values. the frequency of 'a' and 'c' alleles of pou1f1 and stat5a were 0.455 and 0.489, respectively. this population was in hardy-weinburg equilibrium for both loci. there was no significant association between genotypes and breeding values, although pou1f1*b tended to produce higher milk and pou1f1*a showed higher fat and protein percent.