Composition of poorly and non-coagulating bovine milk and effect of calcium addition.

Ninety-nine individual milk samples from 37 cows in lactation week 10-35, selected for producing well or poorly/non-coagulating milk, were compared regarding protein composition, total calcium content, casein micelle size, pH, and coagulating properties after addition of 0·05% CaCl₂. The results showed that a low κ-casein concentration in milk was a risk factor for non-coagulation. CaCl₂ addition improved coagulating properties (coagulation time, curd firmness) of nearly all samples and eliminated differences between poorly/non-coagulating and well-coagulating milk, particularly regarding curd firmness. A second, independent data set with 18 non-coagulating or well-coagulating milk samples were analysed for protein composition, where indications of a similar association with κ-casein was observed.