The proportion of fatty acids in mammary secretion of cows lactating after calving and hormonal induction of lactation.

The changes in the proportion of fatty acids in lacteal fat of cows induced into lactation by 7-day treatment with oestradiol and progesterone were characterized by an increases in the proportion of fatty acids C6--C13: the proportions of C14, C15, C17, C19 fatty acids changed slightly if at all; the proportions of C16, C20 and C22 fatty acids decreased during the first 28 days of lactation. Similar changes in fatty acid composition were found in lacteal fat of cows lactating after calving. These results demonstrated that the hormonal induction of lactation in nonpregnant cows initiates mammary secretion similar to the fatty acid composition in normal cow milk.