Local control of the onset of mammary extraction of plasma triglycerides during lactogenesis in the goat.

In five untreated goats, mammary extraction of plasma triglycerides increased at parturition. In five goats that had as much secretion as possible regularly removed from one mammary gland beginning on d 143 of gestation, the change of triglyceride extraction occurred several d before parturition in the emptied gland but at parturition in the contralateral control gland. The experimentally induced early increase of extraction of plasma triglycerides preceded the increase of prostaglandin F alpha concentration in mammary secretion at parturition, and occurred despite abnormally high concentrations of progesterone in the secretion.