Effects of a GH polymorphism on milk production traits in Modicana and Cinisara cows reared in different feeding systems.

Growth hormone, a polypeptide encoded by the GH gene, is a member of the somatotropin/prolactin family of hormones, which plays an important role on milk production and metabolism. In bovine, a single nucleotide polymorphism (SNP) in exon 5 changes leucine to valine (CTG to GTG) in the mature GH molecule. The purpose of this study was to evaluate, in Modicana and Cinisara cows, the effects of genetic polymorphism at GH locus and its interaction with feeding system on milk traits. A total of 97 individual Modicana blood samples were collected, 65 from a semi extensive and 32 from an extensive farm. A total of 58 Cinisara individual milk samples were collected, 32 from 7 extensive farms and 2…