Effect of STAT5A7Eco81I gene polymorphism on milk yield in Garganica goat breed

Signal transducers and activators of transcription (STATs) are latent cytoplasmic transcription factors. They belong to a 7-member family (STAT1-4, STAT5A, STAT5B, and STAT6) playing a prominent role as mediators of many hormone and cytokines within target cells. STAT5 is known as the main mediator of growth hormone action on target genes; it plays a key-role as mediator of prolactin signalling and can activate transcription of milk protein genes in response to prolactin. A single STAT5 gene was identified in sheep, subsequently two forms, STAT5 and STAT5B have been identified. The STAT5A gene has been mapped to chromosome 19 in goat. Many polymorphisms at STAT5A gene has been investigated in bovine species as candidate markers affecting quantitative traits. To date, only few SNPs at STAT5A gene were detected in goat species and few studies have been conducted. The aims of the present study were to investigate the STAT5A/Eco81I polymorphism in a sample of Garganica goats, an Italian autochthonous breed, and to investigate the possible association between this polymorphism and milk production. Most of Italian goats breeds are represented by small populations with peculiar characteristics and variable productive traits. Garganica breed showed an exceptional ability to adapt to difficult environments and to use poor pasture. This breed originates in the Gargano promontory as a result of a crossbreeding with west European goats. Nowadays, the Garganica goat breed is included in the list of Italian endangered breeds drawn up by the Italian Department for Environment, Food, and Rural Affairs. In the investigated Garganica population, only two out of three possible genotypes were identified, moreover the association between milk yield and different genotypes was investigated.