Response to dietary fat and cholesterol in young adult boars genetically selected for high or low plasma cholesterol.

Twenty-eight young adult boars (age 7 to 8 mo) genetically selected for four generations for high (HG) or low (LG) plasma cholesterol were studied to assess dietary and genetic effects and their interactions on cholesterol metabolism. Boars within a genetic group were paired according to their plasma cholesterol concentration at 8 wk of age and were fed for 15 wk (2.7 kg/d) one of two diets (16.5% fat and 1,156 mg of cholesterol/kg diet, HD; or 3.1% fat and 0 cholesterol diet, LD) in a 2 x 2 factorial arrangement. Plasma total cholesterol (P < .01) and HDL-cholesterol (P < .01) concentrations were higher in boars fed HS (P < .01) and in HG boars (P < .01). There was a trend toward a diet x genotype interaction for plasma HDL-cholesterol (P < .06). Plasma insulin concentration tended to be lower in boars fed HD (P < .09) or HG boars (P < .10). There was a diet x genotype interaction for plasma glucagon (P < .04) concentration and a trend toward an interaction for insulin (P < .07). After 15 wk, all boars were killed by electrocution and exsanguination and measurements were taken. Backfat thickness was greater (P < .01) and carcass length (P < .01) and weights of the four lean cuts (P < .02) were lower in LG than in HG boars. No microscopic atherosclerotic plaques were observed in aorta or coronary arteries. Cholesterol concentration in subcutaneous fat was lower (P < .04) in LG boars, suggesting that cholesterol content of depot fat can be reduced by genetic selection in swine.