Gut microbiota is thought to play a crucial role in nutrient digestion for pigs, especially in processing indigestible polysaccharides in the diets to produce short-chain fatty acids (SCFAs). However, the link between microbiota community structure and phenotypic performances are poorly understood. In the present study, the fecal samples of 105 Jinhua pigs at 105 days of age were clustered into three enterotypes (ETs, ET1, ET2, and ET3) that are subpopulations of distinct bacterial community composition by using 16S rRNA high throughput sequencing. The α-diversity indices (the OTU number and Shannon index) were significantly different among the ETs (p < 0.001). At the genus level, the ET1 group was over-represented by Lactobacillus (17.49%) and Clostridium sensu stricto 1 (11.78%), the ET2 group was over-represented by Clostridium sensu stricto 1 (17.49%) and Bifidobacterium (11.78%), and the ET3 group was over-represented by Bacteroides (18.17%). Significant differences in the fecal contents of butyrate were observed among ETs, with the highest level detected in ET3 and the lowest in ET2 (p < 0.05). Consistently, more copies of the terminal genes for butyrate synthesis, butyrate kinase (Buk) and butyryl coenzyme A (CoA): acetate CoA transferase (But) were detected by qPCR in the fecal samples of the ET3 group as compared to other two groups (p < 0.05). In addition, of the two genes, But was demonstrated to be more relevant to the butyrate content (R = 0.7464) than Buk (R = 0.4905) by correlation analysis. In addition, based on the taxonomic analysis, we found that Faecalibacterium was the most relevant butyrate-producing genera with fecal butyrate contents in Jinhua pigs, followed by Butyricicoccus, Eubacterium, Butyricimonas, Blautia, and Anaerostipes, all of which showed significantly higher richness in ET3 than as compared to ET1 and ET2 (p < 0.05). Collectively, this work presents a first overview of the enterotypes clustering in Jinhua pigs and will help to unravel the functional implications of ETs for the pig’s phenotypic performance and nutrient metabolism.

This study aimed to investigate the effects of low-protein (LP) diets supplemented with sodium butyrate (SB), medium-chain fatty acids (MCT), or n-3 polyunsaturated fatty acids (n-3 PUFA) on the growth performance, immune function, and the microbiome of weaned piglets. A total of 120 healthy weaned piglets ((Landrace × Large White × Duroc); 7.93 ± 0.7 kg initial body weight), were randomly divided into five groups. Each group consisted of six replications with four piglets per replication. Dietary treatments included control diet (CON); LP diet (LP); LP + 0.2% SB diet (LP + SB); LP + 0.2% MCT diet (LP + MCT); and LP + PUFA diet (LP + PUFA). The experimental period lasted for 4 weeks. Compared with the CON diet, LP, LP + SB, LP + MCT, and LP + PUFA diets decreased the final weight and average daily gain (ADG) of piglets (p < 0.05). There were lower (p < 0.05) concentrations of IL-8 and higher (p < 0.05) Glutathione peroxidase (GSH-Px) activity in the plasma of piglets fed with LP + SB, LP + MCT, and LP + PUFA diets than those fed with the LP diet. The piglets in the LP + SB and LP + PUFA groups had lower IKK-alpha (IKKa) mRNA expression in the colonic mucosa compared with those in the CON and LP groups (p < 0.05). The mRNA expression of TLR4 in the colonic mucosa of piglets in the LP + SB, LP + MCT, and LP + PUFA groups was decreased when compared with the CON and LP groups (p < 0.05). The LP + MCT diets increased the gene expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the colonic mucosa of piglets compared with CON, LP, and LP + SB diets (p < 0.05). The abundance of Erysipelotrichaceae in the colonic microbiome of piglets in the LP group was higher than that in the other four groups (p < 0.05). Collectively, this study showed that LP diets supplemented with SB, MCT, or n-3 PUFA reduced plasma inflammatory factor levels, increased plasma GSH-Px activity, and declined mRNA expression of TLR4 and IKKa in the colonic epithelium, whereas it reduced the abundance of Erysipelotrichaceae in the colon of piglets.

This study was conducted to evaluate the effects of a low-protein (LP) diet supplemented with sodium butyrate (SB), medium-chain fatty acids (MCFAs) and n-3 polyunsaturated fatty acids (PUFAs) on nutrient utilization and lipid and amino acid metabolism in weaned pigs. A total of 120 Duroc × Landrace × Yorkshire pigs (initial body weight: 7.93 ± 0.65 kg) were randomly assigned to five dietary treatments, including the control diet (CON), LP diet, LP + 0.2% SB diet (LP + SB), LP + 0.2% MCFA diet (LP + MCFA) and LP + 0.2% n-3 PUFA diet (LP + PUFA). The results show that the LP + MCFA diet increased (p < 0.05) the digestibility of dry matter and total P in pigs compared with the CON and LP diets. In the liver of the pigs, the metabolites involved in sugar metabolism and oxidative phosphorylation significantly changed with the LP diet compared with the CON diet. Compared with the LP diet, the altered metabolites in the liver of the pigs fed with the LP + SB diet were mainly associated with sugar metabolism and pyrimidine metabolism; the altered metabolites in the liver of pigs fed with the LP + MCFA and LP + PUFA diets were mainly associated with lipid metabolism and amino acid metabolism. In addition, the LP + PUFA diet increased (p < 0.05) the concentration of glutamate dehydrogenase in the liver of pigs compared with the LP diet. Furthermore, the LP + MCFA and LP + PUFA diets increased (p < 0.05) the mRNA abundance of sterol regulatory element-binding protein 1 and acetyl-CoA carboxylase in the liver compared with the CON diet. The LP + PUFA diet increased (p < 0.05) mRNA abundances of fatty acid synthase in the liver compared with the CON and LP diets. Collectively, the LP diet supplemented with MCFAs improved nutrient digestibility, and the LP diet supplemented with MCFAs and n-3 PUFAs promoted lipid and amino acid metabolisms.

The objective of this study was to investigate the effects of replacing fishmeal with H. illucens larval meal on the colonic immune homeostasis in weaned piglets in enterotoxigenic Escherichia coli (ETEC)-challenged pig housing. Seventy-two weaned piglets, aged 28 days, were randomly divided into three groups for dietary treatment: the basal diet (negative control, NC), the positive control diet (PC) supplemented with 1445 mg zinc/kg zinc oxide in the basal diet, and the H. illucens larval meal complete replacement of fishmeal in the basal diet (HILM), for 28 days in ETEC-challenged pig housing. The results showed that the relative transcript abundances of ZO-1, pBD2, PR39, and PG1–5 were increased (p < 0.05) in pigs fed the HILM diet compared with those fed the NC diet. In addition, the HILM diet reduced (p < 0.05) the serum contents of IL-8 and increased (p < 0.05) the serum contents of IL-10 and IgG compared with the NC diet. In terms of the molecular mechanisms by which immune homeostasis is improved, the p-NF-κB/ NF-κB ratio and TLR2 protein expression in the colon were decreased (p < 0.05) in pigs fed the HILM diet compared with those fed the NC diet. Compared with the NC diet, the HILM diet reduced (p < 0.05) the protein expression of HDAC3 and HDAC7 in the colon of pigs. The SIRT1, acH3K9, and pH3S10 protein expressions in the colon were the greatest (p < 0.05) in pigs fed the HILM diet compared with the NC diet. HILM diets improved the colonic immune homeostasis in weaned piglets by enhancing the antimicrobial peptide expression, thereby mitigating ETEC challenges in pig housing. Mechanistically, HILM diets promote antimicrobial peptide expression through increased histone acetylation (acH3K9 and pH3S10).

This study aimed to systematically evaluate the effects of low-protein (LP) diets and their associated nutritional interventions on growth performance and intestinal health in weaned piglets through a meta-analysis. Following the PRISMA guidelines, 21 studies were selected from an initial set of 1720 to construct a database. A random-effects model was employed to assess the growth performance and intestinal health of weaned piglets, comparing LP diet with control diet, and LP diet + additive with LP diet alone. Heterogeneity was assessed using the I² statistic, and its sources along with publication bias were explored through meta-regression, subgroup analysis, and Egger’s linear regression. The results show that LP diets (crude protein < 18%) reduced final body weight (p < 0.001), average daily gain (p < 0.001), and gain-to-feed ratio (p < 0.001) of weaned piglets. Additionally, forest plot data show that LP diet (crude protein < 18%) decreased villus height and crypt depth in the jejunum and ileum of weaned piglets (p < 0.05). To mitigate these adverse effects, plant extracts, amino acids (AAs), fatty acids, vitamins, enzymes, and carbohydrates are commonly used as additives. Among these, the results show that LP diets supplemented with AAs and plant extracts increased average daily feed intake (p < 0.001) and ileal crypt depth (p < 0.05). Network meta-analysis further identified AAs and plant extracts as the most effective additives for improving growth performance of weaned piglets. In conclusion, dietary protein levels below 18% negatively affect the growth performance of weaned piglets, and supplementation with AAs or plant extracts represents a promising strategy to counteract these adverse effects.