Net flux of nonesterified fatty acids, cholesterol, triacylglycerol, and glycerol across the portal-drained viscera and liver of pregnant ewes.

The objective of this study was to deter- mine the pattern of nutrient flux across portal-drained viscera (PDV) and liver in ewes with varying numbers of fetuses. Catheters were placed in the hepatic portal vein, a branch of the hepatic vein, a mesenteric vein, and the abdominal aorta of each ewe. Plasma flow and net cholesterol, nonesterified fatty acids (NEFA), and glycerol release across the PDV and liver were deter- mined prior to exposure to rams. Ewes were subse- quently mated. Two ewes were not pregnant, six ewes gave birth to singles, and 11 ewes gave birth to twins. Additional measurements were taken 103, 82, 61, 39, 19, and 6 d before parturition. There was a net PDV uptake of nonesterified cholesterol in the nonpregnant ewes and a net release in the ewes with singles and twins. Net nonesterified cholesterol hepatic release did not differ with days from parturition (P = .77). There was a net hepatic release of nonesterified cholesterol in the ewes with twins and a net hepatic uptake in the ewes with singles and in nonpregnant ewes (P = .03). There was a net PDV release of NEFA; however, it did not differ with litter size (P = .59) or days from parturition (P = .63). Hepatic NEFA uptake increased 2 Names are necessary to report factually on available data; how- ever, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. 3