Effect of k-casein polymorphism on milk composition in the orobica goat

The aim of this work was to study the effects of isoelectrofocusing (IEF) milk protein variants on milk composition in the Italian Orobica goat breed, which is characterized by a rather high frequency of the k-casein (CSN3) B IEF allele. Significant associations were found between the IEF phenotype and protein and casein percentages. A favorable effect of the CSN3 BIEF variant was found for both protein and casein percentages, with a codominance trend for the 3 phenotypes: BB > AB > AA. Depending on the selection purpose, emphasis could be given to different k-casein variants in breeding. The high frequency of BIEF could be exploited in breeding strategies to improve the protein and casein percentages when cheese making is a selection objective.