Brownhill J, Stewart H J, Thompson G E
J Physiol. 1985 Sep;366:291-8. doi: 10.1113/jphysiol.1985.sp015798.
Late-pregnant goats were separated into two groups. A control group of four goats had small (approximately 3 ml) volumes of secretion expelled from one mammary gland at infrequent intervals between day 130 of gestation and parturition. An experimental group of five goats had as much secretion as possible removed from both glands twice daily beginning on day 137 of gestation and continuing until parturition. After parturition, both groups were milked twice daily. Regular 'milking out' before parturition stimulated secretion of triglyceride by the mammary gland, and most of the fatty acids secreted in the triglyceride before parturition had a chain length of 18 carbons. Secretion of 6-14-carbon chain-length fatty acids in the milk triglycerides increased after parturition. There was no evidence that the onset of secretion of medium-chain and long-chain fatty acids occurred at different times in the control animals. It is concluded that the onset of secretion of medium-chain and long-chain fatty acids in milk triglycerides can be dissociated, although both are normally synchronized with parturition. Removal of secretion by the offspring at parturition may be a stimulus for the onset of secretion of long-chain fatty acids, but the onset of secretion of medium-chain fatty acids is brought about by some other mechanism.
妊娠后期的山羊被分成两组。对照组有4只山羊，在妊娠130天至分娩期间，一个乳腺偶尔排出少量（约3毫升）分泌物。实验组有5只山羊，从妊娠137天开始，每天两次尽可能多地从两个乳腺中排出分泌物，持续到分娩。分娩后，两组均每天挤奶两次。分娩前定期“排空”刺激乳腺分泌甘油三酯，分娩前甘油三酯中分泌的大多数脂肪酸碳链长度为18个碳。分娩后，乳甘油三酯中碳链长度为6 - 14个碳的脂肪酸分泌增加。没有证据表明对照动物中中链和长链脂肪酸的分泌起始时间不同。结论是，乳甘油三酯中中链和长链脂肪酸的分泌起始可以分离，尽管两者通常都与分娩同步。分娩时后代对分泌物的清除可能是长链脂肪酸分泌起始的刺激因素，但中链脂肪酸分泌的起始是由其他某种机制引起的。
