Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: June 26, 1996
Publication Date: N/A
Technical Abstract: In late pregnancy, approximately 40% of the increase in heat production can be attributed to increases in heat production by nonreproductive tissues. The objective of this study was to determine the pattern of oxygen consumption by the portal drained viscera and liver during pregnancy to allow for an estimation of the extent to which these tissues contribute to the increase in energy requirement. Catheters were surgically placed in the portal vein, a branch of the hepatic vein, a mesenteric vein, and the abdominal aorta of 19 ewes. Oxygen consumption by the PDV and liver were subsequently measured before breeding and at 6, 9, 12, 15, 18, and 20 wk after breeding. Hepatic arterial blood flow was not influenced by litter size (P=.15) or stage of pregnancy (P=.18). Portal and hepatic venous blood flow increased during pregnancy and peaked at 18 wk. There was a greater increase in twin than in single bearing ewes (P<.04). Arterial oxygen concentration and concentration differences between vessels were not affected by litter size (P>.16) or by stage of pregnancy (P>.13). Hepatic and PDV oxygen consumption increased with increased ad libitum feed intake. Hepatic oxygen consumption was greater in late pregnancy (P=.07) and was greater in ewes with twins (P=.02). The increase in hepatic oxygen consumption occurs approximately 63 d earlier in ewes with twins than in ewes with a single. These data suggest that in ewes with a single fetus, 25% of the increase in heat production in late pregnancy can be attributed to increased liver metabolism.