Study of Polymorphism in STAT5b Gene and Its Association with Milk Production Traits in Holstein Cows of Khorasan Razavi Province

In order to study STAT5b gene polymorphisms and its association with milk production traits in Holstein dairy cows in Khorasan Razavi Province، blood samples were collected from 150 Holstein cows from six herds in Khorasan Razavi Province. DNA was extracted using modified the salting out-Chloroform method and polymerase chain reactions (PCR) were carried out by specific primer pairs for amplification of a fragment of 337 bp from part of exon 16 of STAT5b gene. All animals were genotyped by single stranded conformation polymorphism (SSCP) analyses by Acrylamide gel and using silver staining. Five SSCP patterns (genotypes) of AA، BB، CC، AB، and AD were identified with the frequencies of 0. 0667، 0. 1933، 0. 2067، 0. 4466، and 0. 867، respectively. Statistical data was analyzed using the POPGENE software. Chi-square test (χ2) showed that this population was not in the Hardy-Weinberg equilibrium. Effective allele numbers (Ne) and Shannon’s information index (I) were 3. 0366 and 1. 1928، respectively. Results showed that SNPs were significantly associated with milk yield in Khorasan Razavi Holstein cows (P <0•0004). The cows with combination genotype CC had the highest milk yield. These results suggested that the STAT5b may be a potential genetic marker for milk production selecting. The association between polymorphism in this gene with milk fat and milk protein percentage was not significant