Relationship of Pit-1 polymorphisms with growth traits in Chinese Cattle

The Pit-1 gene was studied as a candidate for genetic markers of growth traits in Chinese cattle in this study. The single-strand conformation polymorphism method was used to identify polymorphism in the Pit-1 intron 5. One single nucleotide polymorphism, Pit1I5, was found in intron 5.The frequencies of alleles AB of Nanyang cattle(NY), Qinchuan cattle(QC), Jiaxianhong cattle(JXH), Xizhen cattle(XZ), Luxi cattle(LX) and Holstein cow(H) populations were 0.444/0.556, 0.477/0.523, 0.538/0.462, 0.421/0.579, 0.523/0.477, 0.475/0.525 respectively. Associations of the polymorphisms with growth traits in Nanyang cattle were analyzed using a general linear model procedure. The following parameters were greater in individuals with an AA genotype than with an AB genotype: body weight, average day gain, body height, chest girth at 6, 12, 18 and 24 months (P<0.01). Body weight and body size also showed a trend of allele B > allele A in other age groups. Therefore, genotype BB maybe a dominant genotype and allele B may be a dominant allele. These results imply that allele B of Pit-1 gene likely positively affects growth traits.