Effects of manipulating dietary protein and energy intake on energy balance and thermogenesis in the pig.
Weight maintenance was achieved by feeding either restricted amounts of a high-protein diet (HP) or ad libitum amounts of low-protein diet (LP) to 6 and 20 kp pigs for up to 42 days. In all cases, LP animals consumed approximately three times as much energy as the HP animals but in the 20-kp pigs, almost all (70%) of this excess was deposited in the carcass as fat. In 6-kg pigs fed the LP diet, changes in body energy content accounted for only a small fraction (27%) of the total energy intake; a large difference in energy expenditure was seen between these animals and the HP group, which was attributed to differences in dietary-induced thermogenesis. Six-kilogram LP pigs showed elevated plasma triiodothyronine levels and hepatic mitochondrial alpha-glycerophosphate dehydrogenase activity and an enhanced sensitivity to the in vitro lipolytic effects of norephinephrine (NE) on adipose tissue. These changes are similar to those observed in rats exhibiting dietary-induced thermogenesis and the relevance of these findings to the increased heat production of LP pigs is discussed.
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism; D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects; D001835:Body Weight; D004032:Diet; D004044:Dietary Proteins / Q000494:pharmacology*; D002149:Energy Intake; D004734:Energy Metabolism / Q000187:drug effects; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005260:Female; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D013552:Swine / Q000378:metabolism*; D014284:Triiodothyronine / Q000097:blood
D004044:Dietary Proteins; D005230:Fatty Acids, Nonesterified; D014284:Triiodothyronine; D005993:Glycerolphosphate Dehydrogenase; D009638:Norepinephrine