Relationship Between California Mastitis Test Reaction and Composition of Milk from Opposite Quarters

Abstract

The composition of the milk from opposite quarters showed highly significant decreases in total solids, fat, nonfat solids, and lactose, due to subclinical mastitis as measured by the California Mastitis Test (CMT). For the comparison between negative CMT reactions and those judged to be three, the average decreases amounted to 1.07% T. S., 0.45% fat, 0.57% SNF, 0.77% lactose. Less significance could be attributed to the differences observed for protein. Loss in casein was offset by increases in the serum proteins. Chlorides showed significant increases along with the pH of the milk as the CMT reaction became more severe. The variability of the SNF measured by a density method (bead test) from the gravimetric method, used as a standard, increased with the CMT reaction. When the reduced level in milk production was combined with the decreased fat test, an average loss of 48% in total fat production was found for opposite quarters showing CMT three vs. negative reactions.