Low-protein diets supplemented with casein hydrolysate favor the microbiota and enhance the mucosal humoral immunity in the colon of pigs

Abstract

Background High-protein diets can increase the colonic health risks. A moderate reduction of dietary crude-protein (CP) level can improve the colonic bacterial community and mucosal immunity of pigs. However, greatly reducing the dietary CP level, even supplemented with all amino acids (AAs), detrimentally affects the colonic health, which may be due to the lack of protein-derived peptides. Therefore, this study evaluated the effects of supplementation of casein hydrolysate (peptide source) in low-protein (LP) diets, in comparison with AAs supplementation, on the colonic microbiota, microbial metabolites and mucosal immunity in pigs, aiming to determine whether a supplementation of casein hydrolysate can improve colonic health under very LP level. Twenty-one pigs (initial BW 19.90 ± 1.00 kg, 63 ± 1 days of age) were assigned to three groups and fed with control diet (16% CP), LP diets (13% CP) supplemented with free AAs (LPA) or casein hydrolysate (LPC) for 4 weeks. Results Compared with control diet, LPA and LPC diet decreased the relative abundance of Streptococcus and Escherichia coli, and LPC diet further decreased the relative abundance of Proteobacteria. LPC diet also increased the relative abundance of Lactobacillus reuteri. Both LP diets decreased concentrations of ammonia and cadaverine, and LPC diet also reduced concentrations of putrescine, phenol and indole. Moreover, LPC diet increased total short-chain fatty acid concentration. In comparison with control diet, both LP diets decreased protein expressions of Toll-like receptor-4, nuclear factor-κB, interleukin-1β and tumor necrosis factor-α, and LPC diet further decreased protein expressions of nucleotide-binding oligomerization domain protein-1 and interferon-γ. LPC diet also increased protein expressions of G-protein coupled receptor-43, interleukin-4, transforming growth factor-β, immunoglobulin A and mucin-4, which are indicators for mucosal defense activity. Conclusions The results showed that supplementing casein hydrolysate showed beneficial effects on the colonic microbiota and mucosal immunity and barrier function in comparison with supplementing free AAs in LP diets. These findings may provide new framework for future nutritional interventions for colon health in pigs.

Evaluation of the in vitro effects of the increasing inclusion levels of yeast β-glucan, a casein hydrolysate and its 5 kDa retentate on selected bacterial populations and strains commonly found in the gastrointestinal tract of pigs

“…Dietary supplementation of weaned and growing pigs with casein-derived peptides was also associated with an increase in butyrate production. 49,50 YBG, contrarily, decreased butyrate concentration. This is probably linked with the reduction of certain members of the microbiota due to YBG supplementation.…”

“…The ability of 5kDaR to stimulate lactobacilli growth within a complex microbial community was in agreement with previous studies in which the ileal and colonic counts of this bacterial population were increased in weaned and growing pigs supplemented with casein-derived peptides. 49,50 An additional bacterial group that was measured in the batch fermentation assay was Prevotella spp. which is the predominant genus in weaned pigs.…”

Enzyme-Treated Soybean Meal Replacing Extruded Full-Fat Soybean Affects Nitrogen Digestibility, Cecal Fermentation Characteristics and Bacterial Community of Newly Weaned Piglets

“…As the main nitrogen source of the intestinal microbe, dietary protein has been proven to significantly change the bacterial community. Wang et al reported that low protein diets improved hindgut health by preventing the proliferation of pathogenic bacteria ( 22 ). A better digestible protein source also reduced the risk of colitis under the same protein level ( 23 , 24 ).…”

Mutual interaction between gut microbiota and protein/amino acid metabolism for host mucosal immunity and health

“…In addition, protein or amino acid restriction and amino acid supplementation also changed the composition of intestinal microbiota. Wang et al. (2019) reported that low-protein diets with casein hydrolysate reduced the concentrations of putrescine, phenol, and indole compounds in the colonic digesta of pigs and the relative abundance of L. reuteri in the colon of pigs at the species level, when compared with diets added with free amino acids.…”