Positional Distribution of Fatty Acids in Triglycerides from Prepartum Mammary Gland Secretion and Early Postpartum Milk

Triglycerides from mammary gland secretion collected at 24, 17, 10, 7, and 3.5 days prepartum and from milk collected at 0 (2 h), 1, 2, 3, 4, 5, 6, 7, 14, 21, and 28 days postpartum were subjected to fatty acid and stereospecific analysis. Prepartum mammary gland secretion differed from normal milk in that it contained approximately twice the amount of 16:0 and larger than normal amounts of 14:0. This was compensated for by less amounts of other mediumchain, short-chain, 18:0, and 18:1 acids. Positional distribution of fatty acids in milk from 1 day postpartum onward generally followed the specific pattern normally encountered for milk triglycerides. With exception of the first sample at 24 days prepartum, mammary gland secretion had medium-chain acids at 8:0, 10:0, 12:0, and sometimes 14:0 preferentially esterified at the sn-3position rather than the sn-2-position. Relationships were linear between content of fatty acids at the three stereospecific positions and content of the same acid in triglycerides. These significant relationships are represented by regression equations. With varying triglyceride fatty acid content, fatty acid content at the three positions did not change at the same rate. PARODI .