Effects of ileo-rectal anastomosis on cholesterol metabolism in pigs fed either casein or extruded soya beans

Abstract

The importance of legume proteins in the cholesterol metabolism has been recognized in different animals, but the contribution of large intestine to this process is still unclear. The present study was undertaken to compare a casein based diet (C) with a diet, where 60% of the protein supplied by casein was replaced by extruded soybean (ES) on cholesterol metabolism of pigs with (I) and without ileo-rectal anastomosis (IRA). Four groups of six growing pigs (28.0 kg) were assigned to the treatments. All the animals presented a moderate hypercholesterolemia and there were no significant differences, due to the protein source or IRA, in LDL- and HDL- cholesterol plasma concentrations. ES significantly depressed (P0.01) total, free and esters of hepatic cholesterol and increased (P<0.01) hepatic total lipids concentration. There were significant (P<0.05) interactions between diet and IRA on HMG CoA reductase and cholesterol 7- hydroxylase activities, but 27–hydroxylase activity was unaffected. Feeding ES showed a tendency (P=0.056) to decrease the activity of LDL liver receptors, depressed free (P0.05), total cholesterol (P0.01) and total bile acid concentration in bile (P0,001), and increased (P0.05) neutral sterols fecal output. There were interactions effects (P0.05) between diet and IRA in the proportion of microbial sterols, bile acid fecal output and proportion of primary and secondary fecal acids. Nevertheless the effects over hepatic cholesterol and neutral sterol output promoted by ES diets, it wasn’t verified any hypocholesterolemic effect, which could be more related with soybean protein structure and LDL receptors modulation.