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

The aim of this work was to study the effects of iso- electrofocusing (IEF) milk protein variants on milk composition in the Italian Orobica goat breed, which is characterized by a rather high frequency of the κ-casein (CSN3) BIEF allele. Significant associations were found between the IEF phenotype and protein and casein per- centages. 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 κ-casein variants in breeding. The high frequency of BIEF could be exploited in breed- ing strategies to improve the protein and casein per- centages when cheese making is a selection objective.