Preliminary study on the STAT5A/AvaI polymorphism in Jersey cows: relation with milk production traits

In this study the STAT5A/Aval polymorphism was investigated with PCR-RFLP in a sample of 126 Jersey cattle reared in southern Italy This polymorphism is localized in the coding region of the bovine STAT5A gene It is a substitution C -> T a at position 6853 within the exon 7 Only two out of three possible genotypes for the C/T SNP were identified The overall frequencies of alleles C and T were 0 76 and 0 24 respectively In order to study the relationship between STAT5A/Aval polymorphism and milk performance traits, the data for a 305-day milk production that include milk yield (MY), protein and fat yield (PY and FY respectively), fat and protein percentage (FC and PC respectively) were used Significant differences between the two genotypes were found in MY, FY and PY (P<0 01) The CC cows produced more milk than CT ones (6218 09 vs 5751 72 kg) Moreover CC cows yielded more fat and protein than CT No significant difference was found in fat and protein content