Association of STAT5A gene polymorphisms with milk yield in primiparous Agerolese cow

Signal transducers and activators of transcription ( STAT) are latent cytoplasmic transcription factors belonging to a seven member family of intracellular factors that mediate actions of many peptide hormones and cytokines within target cells acting as signal transducers in the cytoplasm and transcription a ctivators in the nucleus. STAT5, also known as mammary gland factor (MGF), was discovered initially as a PRL induced transcription factor; it is the main mediator of growth hormone (GH) action on target genes and is a key intracellular mediator of prolacti n signalling pathway being able to activate the transcription of milk protein genes in response to prolactin. Two genetic polymorphisms at STAT5A gene were investigated in a sample of Agerolese cows, an autochthonous Italian cattle breed reared in the prov ince of Naples. So, the aims of the present study were to estimate the allele and genotype frequencies for both SNPs and to investigate the relationship among genotypes and milk yield during first lactation. No genetic variability was found at STAT5A/AvaI locus. At STAT5A/MslI locus the frequencies of T and C alleles were 0.875 and 0.125, respectively.