Mammary secretion of triglycerides in the cow pre-partum.

1. Regular removal of fluid from the mammary gland, before parturition, stimulated its secretion of triglycerides, and particularly C18 fatty acids in the triglycerides, in some individual cows. 2. Cows that did not respond to pre-partum emptying were stimulated to secrete triglycerides by parturition. 3. The onset of secretion of milk triglycerides correlated with the onset of secretion of mammary fluid. 4. No increase in the ratio of C18:1 to C18:0 in the triglycerides, reflecting an onset of mammary desaturase activity, was observed.