Composite milk protein phenotypes in relation to composition and cheesemaking properties of milk

The effects of composite milk protein phenotypes on the composition and cheesemaking properties of milk were studied. Pooled milks from 12 selected groups of Brown cattle with particular phenotype combinations of β-casein (A2A2, A2B), κ-casein (AA, AB, BB) and β-lactoglobulin (AA, BB) were investigated. αs1-Cn BB was common to all animals. Milk collection and cheesemaking trials on a pilot scale were repeated four times during winter 1993. The interaction between all three gene loci (β-Cn, κ-Cn, β-Lg) was found to be highly significant (P < 0.001) for the contents of total protein, casein, whey protein and fat. The casein number was 0–4% (absolute) higher for β-Lg BB milk than for β-Lg AA milk. The relative amount of κ-casein consistently increased from κ-Cn AA to κ-Cn BB. The losses of fat and curd fines in the whey and moisture-adjusted cheese yield were also affected by the genotype combinations. Recovery of milk solids was 3% higher for β-Cn A2B milk than for β-Cn A2A2 milk (P = 0.010).