EN
Casein is the predominant protein in milk of almost all mammalian species. The goat casein fractions (αₛ₁-, β-, αₛ₂-, κ-casein) are coded by the single autosomal genes CSN1S1, CSN2, CSN1S2, and CSN3, which cluster in a DNA segment of about 250 kbp, mapped to chromosome 6. All casein fractions are characterized by high variability. At the four loci, “normal” alleles are associated with a normal or high casein fraction content, whereas “defective” alleles are associated with a medium, low, or zero content of casein fraction in milk. The quality of total casein and, in particular, the calcium-sensitive fraction (αₛ₁-, β-, αₛ₂-) significantly affects the chemical, physical, technological, and nutritional quality of goat’s milk.