Effects of Dietary Protein Level on the Microbial Composition and Metabolomic Profile in Postweaning Piglets

Abstract

Since the human and porcine digestive systems have similar anatomical structures and physiological functions, pigs are a useful animal model for studying human digestive diseases. By investigating intestinal metabolites in piglets after weaning, this study attempted to identify the inherent connection between dietary protein levels and changes in the intestinal microbiota of piglets. Casein was employed as the only source of protein for the piglets in this study to avoid the influence of other protein sources. 14 weaning at 28-day-old piglets ( 6.9 ± 0.19 kg) formed into two dietary groups: 17% casein fed group (LP) and 30% casein fed group (HP). Piglets were allowed to free food and water during the 2-week experiment. Throughout the trial, the piglets’ diarrhea index (1: no diarrhea and 3: watery diarrhea) and food intake were noted during the experiment. We discovered piglets fed a high-protein diet developed diarrhea throughout the duration of the research, whereas piglets fed a normal protein diet did not. In addition, the HP group had lower feed intake and body weight than the control group ( P < 0.05 ). The HP diet influenced the content of short-chain and branched-chain fatty acids in the colon, including acetate and isovaleric acid. The ileal microbiota’s 16S rRNA gene was sequenced, and it was discovered that the relative abundance of gastrointestinal bacteria differed between the HP and control groups. Dietary protein levels influenced bile acid biosynthesis, alpha-linolenic acid metabolism, phospholipid biosynthesis, arachidonic acid metabolism, fatty acid biosynthesis, retinol metabolism, arginine and proline metabolism, pyrimidine metabolism, tryptophan metabolism, and glycine and serine metabolism, according to gas chromatography-mass spectrometry analysis. Furthermore, a correlation analysis of the pooled information revealed a possible link between intestinal metabolites and specific bacteria species. These findings demonstrate that weaned piglets’ microbiota composition and metabolites are modified by a high-protein diet and thus inducing severe postweaning diarrhea and inhibiting growth performance. However, the potential molecular mechanism of this regulation in the growth of piglets remains unclear.

Modulation of Swine Gut Microbiota by Phytogenic Blends and High Concentrations of Casein in a Validated Swine Large Intestinal In Vitro Model

“…Dowley et al show similar results, as they did not observe any significant effects of a casein-containing diet on alpha diversity in the gut microbiota of piglets, although beta diversity was significantly affected [ 69 ]. Gao et al obtained the opposite results, as in their in vivo experiment a diet with a high concentration of casein resulted in significantly lower alpha diversity compared to the control, but there were no differences in beta diversity [ 70 ]. In our study, there was a tendency in decreasing the alpha diversity with casein-containing supplements (both with and without PBs), while with phytobiotics alone there is a trend for an increase, but these differences were not significant.…”

Research progress on anti-stress nutrition strategies in swine

“…Foods with high protein were reported to reduce pepsin activity and acid hydrolysis that hinders food breakdown and gastric emptying ( Mennah-Govela et al., 2020 ). Diarrhea in piglets fed high protein diets is related to undigested protein in the intestine ( Gao et al., 2022 ). With excessive protein fermentation, colonic microbes produce toxic metabolites, such as ammonia, sulfides and indoles ( Windey et al., 2012 ; Rist et al., 2013 ).…”

Effect of Red-Beetroot-Supplemented Diet on Gut Microbiota Composition and Metabolite Profile of Weaned Pigs—A Pilot Study

“…Pathogenic colonization of the gut, a leading cause of diarrhea and death in young pigs at weaning, is thus avoidable via dietary modulation of a healthy gut microbial composition [ 5 , 6 ]. Notably, alteration in the composition and diversity of the gut microbiota by the source and level of protein and fiber can increase or deplete gut microbiota metabolite production and corresponding biological responses [ 7 , 8 , 9 ]. The gut microbiota and metabolite levels in return enhance or inhibit the growth of certain bacteria phyla (e.g., Bacteroidetes, Firmicutes, and Proteobacteria) in the gastrointestinal tract [ 10 , 11 ].…”