Dietary Fat Content and Fiber Type Modulate Hind Gut Microbial Community and Metabolic Markers in the Pig

Abstract

Obesity leads to changes in the gut microbial community which contribute to the metabolic dysregulation in obesity. Dietary fat and fiber affect the caloric density of foods. The impact of dietary fat content and fiber type on the microbial community in the hind gut is unknown. Effect of dietary fat level and fiber type on hindgut microbiota and volatile fatty acid (VFA) profiles was investigated. Expression of metabolic marker genes in the gut, adipose tissue and liver was determined. A 2×2 experiment was conducted in pigs fed at two dietary fat levels (5% or 17.5% swine grease) and two fiber types (4% inulin, fermentable fructo-oligosaccharide or 4% solka floc, non-fermentable cellulose). High fat diets (HFD) resulted in a higher (P<0.05) total body weight gain, feed efficiency and back fat accumulation than the low fat diet. Feeding of inulin, but not solka floc, attenuated (P<0.05) the HFD-induced higher body weight gain and fat mass accumulation. Inulin feeding tended to lead to higher total VFA production in the cecum and resulted in a higher (P<0.05) expression of acyl coA oxidase (ACO), a marker of peroxisomal β-oxidation. Inulin feeding also resulted in lower expression of sterol regulatory element binding protein 1c (SREBP-1c), a marker of lipid anabolism. Bacteria community structure characterized by DGGE analysis of PCR amplified 16S rRNA gene fragments showed that inulin feeding resulted in greater bacterial population richness than solka floc feeding. Cluster analysis of pairwise Dice similarity comparisons of the DGGE profiles showed grouping by fiber type but not the level of dietary fat. Canonical correspondence analysis (CCA) of PCR- DGGE profiles showed that inulin feeding negatively correlated with back fat thickness. This study suggests a strong interplay between dietary fat level and fiber type in determining susceptibility to obesity.

NMR-based metabolomics highlights differences in plasma metabolites in pigs exhibiting diet-induced differences in adiposity

“…Irrespective of line, there was a marked decrease in BW and body fat content with the HF diet. This observation is in agreement with previous studies showing a negative effect of fibre inclusion in high-fat diet on adiposity in pigs [26,27] and rats [28]. Fig.…”

“…In the present study, the lower plasma concentration of β-hydroxybutyrate observed with the HF diet may sign for a variation in the hepatic oxidation of fatty acids. Previous studies have suggested that insoluble fibres induce fatty acid oxidation in the liver of mice [31] and pigs [27]. Altogether, these findings support the view that the HF diet can drive different metabolic changes at the hepatic level.…”

Effect of dietary fiber type on intestinal nutrient digestibility and hindgut fermentation of diets fed to finishing pigs

“…However, the CMC is a low-fermentable and high-viscous carboxymethylcellulose and increases the AID of CP in weaned pigs (Fledderus et al, 2007). The INU is a highfermentable, low-viscous fructan (Yan et al, 2013) and is fermented by microbial populations (Bach Knudsen and Hansen, 1991). The present study was designed to study the effects of incorporation of 5% INU or CMC into a corn-soybean meal diet of finishing pigs.…”

“…The INU with low viscosity increases digesta passage rate (Yan et al, 2013). Quick digesta passage rate causes less time for substrate digested by CHO enzymes (Hooda et al, 2011), thereby reducing 9.4% of the CHO ileal digestibility compared to the control diet.…”

“…Specific effects of functional or structural properties can be differentiated by using of feeding purified fiber fractions, such as low viscous, high fermentable inulin or high viscous, low fermentable sodium carboxymethylcellulose (Hooda et al, 2011;Yan et al, 2013). Moreover, viscosity and fermentability of dietary fiber interact to affect the digestibility and fermentation of nutrients and energy in pigs (Hooda et al, 2011).…”