Abstract
A study on the mechanism of abnormal milk secretion, which is one of the inflammatory response of the mammary gland, was conducted by administrating estradiol monobenzoate (EB) or bacteria to lactating rats.
In the first experiment, lysozyme and glucosamine in the mammary gland, and pH and leukocyte count in the milk were determined at intervals 5, 8, 24 and 48 hours after EB administration. The con-centration of lysozyme and glucosamine in the mammary gland increased gradually with the lapse of time. The highest levels of leukocyte count and pH of milk were found at 8 hours after the first injection of EB.
In the second experiment, chemical components in the mammary gland as same in the first experiment were determined at intervals of 5, 8, 24 and 48 hours after administrating EB +Staphylococcus aureus or EB+Streptococcus fecalis. Lysozyme and glucosamine in the mammary gland of two groups administrated EB+ bacteria increased gradually with the lapse of time.
In the third experiment, the inhibitory action of lysozyme on bacterial growth was examined with Escherichia coli, two strains of Staphylococcus aureus, Streptococcus bovis and Streptococcus fecalis isolated from field materials of bovine mastitis. That is, 1 ml of bacterial suspension incubated in broth for 24 hours and 1 ml of 5 to 250 pglml of lysozyme were mixed, and reacted at 37°C for 1 hour. They were incubated with heart infusion broth for 24 hours and numbers of grown bacteria were shown by turbidity in broth medium. Turbidity measurements were read as optical density at 660 mp with spectrophotometer. The rate of growth inhibitory action of the lysozyme on each bacteria was 6 to 30% to Escheri-chia coli, 16 to 62% to Streptococcus bovis, 8 to 46% to Staphylococcus aureus (yellow colony) and 23 to 57% to Staphylococcus auseus (white colony) and Streptococcus fecalis was a low rate of 10 to 20% and no difference was found along the concentration of lysozyme.
