Relationship of PIT1 gene polymorphism with dairy traits of Iranian Holstein bulls North West and Karaj breeding centers

The aim of this study was to determine to Pituitary-specific transcription factor (Pit1) gene polymorphism relationship with milk production in Iranian Holstein dairy cows. For this purpose, blood samples were collected from 110 proof and un-proof Holstein bulls from North West and Tehran breeding centers of Iran. After performing extraction steps using modified phenol-chloroform method, PITI exon 6 polymorphism was determined with PCR-RFLP and HifI restriction enzyme. Two alleles and three genotypes were observed. Hinf1+ (G) allele and GG genotype were the more frequent. Allelic and genotypic variations in years do not show a specific trend, and for most of the years, the G allele was more frequent. The results of analysis of variance showed that PitI-HinfI polymorphism was not significant effect on milk, fat, protein production, fat percentage and protein content (p>0.05). Allelic replacement effect results showed that allele change from G to A did not have a significant effect on any of the studied traits. Based on the results of this study, it can be concluded that for the use of this gene in the of milk production traits improvement, further research is needed.