Investigating the genetic polymorphism of sheep milk proteins: an useful tool for dairy production

Sheep is the second most important dairy species after cow all over the world, especially in the Mediterranean and Middle East regions. In some countries, the hard environmental conditions require a peculiar adaptation and in these contexts, sheep are able to provide higher quality protein than cattle. In least developed countries, the number of dairy sheep and ovine milk production is progressively increasing. In order to improve dairy productions, in particular those with local connotation, it is necessary to deepen the current acquisitions on milk quality and rheological properties. The genetic polymorphisms of milk proteins are often associated to quantitative and qualitative parameters in milk being potential candidate markers that should be included in breeding strategies similarly to as experienced already in cattle. Due to the current and growing interest on this topic and considering the large number of new information, the aim of this study was to review the literature on sheep milk protein polymorphisms with a particular emphasis to recent findings to give scientists an useful support. Moreover, the effects of different protein variants on milk yield and composition were discussed.