A large-scale survey of milks from healthy and mastitic bovine quarters was undertaken to establish the influence of mastitic infection on milk lipase activity and free fatty acid (FFA) level. Mastitic milks tended to have higher FFA levels, but lower lipoprotein lipase activities compared with milk from healthy quarters. These effects became significant at relatively severe levels of infection. The elevated FFA was attributable to higher FFA levels on secretion and to greater lipolysis during storage. Levels of carboxylesterase activity increased with severity of mastitis and showed high positive correlation with mastitis indices.
Marked increases in carboxylesterase, N-acetyl-β-D-glucosaminidase and phospholipase occurred following the induction of mastitis by intramammary infusion of Escherichia, coli endotoxin, in parallel with changes in somatic cell count and other mastitis indices. Relatively little change in lipoprotein lipase activity was observed.