Use of Carbohydrate and Fat as Energy Source by Obese and Lean Swine

Abstract

Genetically obese and lean pigs were fed isonitrogenous-isoenergetic (digestible energy) amounts of a high or low fat diet from 25 kg body weight. Obese pigs gained less and required more feed per unit gain than lean pigs. Lean pigs were more muscular with less fat than obese pigs. Obese pigs utilized more dietary amino acids for energy (greater plasma urea N) than did lean pigs. Weight gain was similar at all intermediate periods in obese pigs fed the two diets. However, gain tended (P less than or equal to .10) to be greater and the ratio of dietary energy intake to gain tended (P less than or equal to .10) to be less in obese pigs fed high compared with low fat diets. Similar results were observed in lean pigs fed the two diets. The high fat diet produced more carcass adipose tissue deposition in both strains after 20 wk of feeding (detectable by ultrasound at 14, but not at 7 wk). Adipose tissue lipogenic rate (glucose incorporation) was similarly depressed by fat feeding in both obese and lean pigs. Obese and lean pigs both utilized dietary carbohydrate and fat differentially but there was no indication of genetic divergence regarding this utilization. In both strains of pigs, energy from the fat-enriched diet was preferentially partitioned into carcass adipose tissue.

Dietary fat source affects metabolism of fatty acids in pigs as evaluated by altered expression of lipogenic genes in liver and adipose tissues

“…In contrast to the liver, pigs fed with the no fat-added diet (NF diet) showed the highest mRNA abundance in adipose tissue of genes involved in the synthesis of palmitic acid (ACACA and FASN) and also a gene involved in FA desaturation (SCD). These results agree with the higher lipogenic rate observed by Smith et al (1996) in cultured adipocytes isolated from pigs fed a cornstarch diet as compared to pigs fed a 10% fat-added diet, and also agrees with the findings of Mersmann et al (1984) who measured adipose tissue lipogenesis comparing carbohydrate and fat as energy source. In the present study, the higher SCD mRNA abundance in adipose tissue with the NF diet showed a different response pattern to what was observed in the liver.…”

Plasma metabolite and hormone concentrations in Southdown ram hoggets from lines divergently selected on the basis of backfat thickness

“…), and when they are fed above maintenance, but not during a prolonged period of sub-maintenance feeding (Bremmers et al 1988). Similar differences have been observed in other selection lines, low plasma urea concentrations being associated with selection for reduced fatness in pigs (Mersmann et al 1984), for increased fleeceweight in Romney sheep (McCutcheon et al 1987;Clark et al 1989), and for increased yields of milk or milk solids in dairy cattle (Tilakaratne et al 1980;Sejrsen et al 1984;Sinnett-Smith et al 1987). Breed differences in plasma urea have also been reported, Suffolk lambs having higher concentrations than the leaner Texellambs (Hanrahan 1986).…”

Plasma metabolite and hormone concentrations as predictors of genetic merit for lean meat production in sheep: Effects of metabolic challenges and fasting

“…Mersmann et al (1984) suggested that differences in plasma urea concentrations observed between lean and fat selection lines of pigs occurred as a result of more efficient use of amino acids for protein synthesis, and consequent reduced requirement to deaminate amino acids, in the lean line. Alternative explanations for differences in plasma urea concentrations are that urea excretion rate and/or the urea distribution space differ between the lines.…”

“…These include dairy cows selected for high versus low milk yield (Sejrsen et al 1984;Sinnett-Smith et al 1987), Romney sheep selected for high fleeceweight versus controls (McCutcheon et al 1987;Clark et al 1989), and pigs selected for low versus high fatness (Mersmann et al 1984). In each instance, the less productive line maintained higher plasma concentrations of urea Studies in humans (Bergman et al 1981), pigs (Wangsness et al 1977), cattle (McCann & Reimers 1985a,b), and sheep (McNiven 1984;Munro et al 1984) have demonstrated that obese individuals or lines have higher basal concentrations of glucose and/or insulin, reduced peripheral sensitivity to insulin and, in some instances, increased pancreatic sensitivity to glucose.…”