Low Protein Diet Improves Meat Quality and Modulates the Composition of Gut Microbiota in Finishing Pigs

Blended-protein changes body weight gain and intestinal tissue morphology in rats by regulating arachidonic acid metabolism and secondary bile acid biosynthesis induced by gut microbiota

PURPOSE

The impact of dietary nutrients on body growth performance and the composition of gut microbes and metabolites is well-established. In this study, we aimed to determine whether dietary protein can regulate the physiological indexes and changes the intestinal tissue morphology in rats, and if dietary protein was a crucial regulatory factor for the composition, function, and metabolic pathways of the gut microbiota.

METHOD

A total of thirty male Sprague Dawley (SD) rats (inbred strain, weighted 110 ± 10 g) were randomly assigned to receive diets containing animal-based protein (whey protein, WP), plant-based protein (soybean protein, SP), or a blended protein (soybean-whey proteins, S-WP) for a duration of 8 weeks. To investigate the effects of various protein supplement sources on gut microbiota and metabolites, we performed a high throughput 16S rDNA sequencing association study and fecal metabolomics profiling on the SD rats. Additionally, we performed analyses of growth indexes, serum biochemical indexes, and intestinal morphology.

RESULTS

The rats in S-WP and WP group exhibited a significantly higher body weight and digestibility of dietary protein compared to the SP group (P < 0.05). The serum total protein content of rats in the WP and S-WP groups was significantly higher (P < 0.05) than that in SP group, and the SP group exhibited significantly lower (P < 0.05) serum blood glucose levels compared to the other two groups. The morphological data showed the rats in the S-WP group exhibited significantly longer villus height and shallower crypt depth (P < 0.05) than the SP group. The gut microbial diversity of the SP and S-WP groups exhibited a higher level than that of the WP group, and the microbiomes of the WP and S-WP groups are more similar compared to those of the SP group. The Arachidonic acid metabolism pathway is the most significant KEGG pathway when comparing the WP group and the SP group, as well as when comparing the SP group and the S-WP group.

CONCLUSION

The type of dietary proteins exerted a significant impact on the physiological indices of SD rats. Intake of S-WP diet can enhance energy provision, improve the body's digestion and absorption of nutrients, as well as promote intestinal tissue morphology. In addition, dietary protein plays a crucial role in modulating fecal metabolites by regulating the composition of the gut microbiota. Metabolomics analysis revealed that the changes in the levels of arachidonic acid metabolites and secondary bile acid metabolite induced by Clostridium_sensu_stricto_1 and [Eubacterium]_coprostanoligenes_group maybe the primarily causes of intestinal morphological differences.

Multi-omics reveal the effects and regulatory mechanism of dietary neutral detergent fiber supplementation on carcass characteristics, amino acid profiles, and meat quality of finishing pigs

This study aimed to reveal the effects and regulatory mechanism of dietary NDF on the performance of pigs by multi-omics analysis. Results showed that 16 % dietary NDF significantly improved meat quality, increased flavor amino acid content, and reduced backfat thickness and the feed-to-gain ratio. 16S rDNA sequencing showed that 16 % NDF significantly increased the abundance of Akkermansia, Lachnoclostridium, and Ruminococcus. Transcript analysis showed that genes related to muscle development and lipid metabolism were significantly modified. Metabonomic analysis showed that 16 % NDF significantly increased amino and fatty acid related metabolites. Correlation analysis suggested that 16 % NDF treatment may alter the gut microbiota and metabolites, regulate the expression of genes related to lipid and amino metabolism, and ultimately affect the flavor and performance of pigs. This study provides a novel understanding about the effect and regulatory mechanism of NDF supplements on the finishing pigs and a relevant reference for the improvement of diet formulation.

Multispecies probiotic supplementation in diet with reduced crude protein levels altered the composition and function of gut microbiome and restored microbiome-derived metabolites in growing pigs

Both crude protein (CP) and probiotics can modulate the gut microbiome of the host, thus conferring beneficial effects. However, the benefits of low CP diet supplemented with multispecies probiotics on gut microbiome and its metabolites have not been investigated in pigs. Thus, we investigated the combinatory effects of low CP diet supplemented with multispecies probiotics on gut microbiome composition, function, and microbial metabolites in growing pigs. In total, 140 6 week-old piglets (Landrace × Yorkshire × Duroc) were used in this study. The pigs were divided into four groups with a 2 × 2 factorial design based on their diets: normal-level protein diet (16% CP; NP), low-level protein diet (14% CP; LP), NP with multispecies probiotics (NP-P), and LP with multispecies probiotics (LP-P). After the feeding trial, the fecal samples of the pigs were analyzed. The fecal scores were improved by the probiotic supplementation, especially in LP-P group. We also observed a probiotic-mediated alteration in the gut microbiome of pigs. In addition, LP-P group showed higher species richness and diversity compared with other groups. The addition of multispecies probiotics in low CP diet also enhanced gut microbiota metabolites production, such as short-chain fatty acids (SCFAs) and polyamines. Correlation analysis revealed that Oscillospiraceae UCG-002, Eubacterium coprostanoligenes, Lachnospiraceae NK4A136 group, and Muribaculaceae were positively associated with SCFAs; and Prevotella, Eubacterium ruminantium, Catenibacterium, Alloprevotella, Prevotellaceae NK3B31 group, Roseburia, Butyrivibrio, and Dialister were positively correlated with polyamines. Supplementation with multispecies probiotics modulated the function of the gut microbiome by upregulating the pathways for protein digestion and utilization, potentially contributing to enriched metabolite production in the gut. The results of this study demonstrate that supplementation with multispecies probiotics may complement the beneficial effects of low CP levels in pig feed. These findings may help formulate sustainable feeding strategies for swine production.

Long-Term Protein Restriction Modulates Lipid Metabolism in White Adipose Tissues and Alters Colonic Microbiota of Shaziling Pigs

Obesity is a matter of concern to the public. Abundant evidence has been accumulated that nutritional intervention is a promising strategy to address this health issue. The objective of this study is to investigate alterations in the lipid metabolism in white adipose tissues and the gut microbiota of Shaziling pigs challenged by long-term protein restriction. Results showed that compared with the control group, reducing the protein level by 20% (−20%) increased the mRNA abundance of FABP4 in white adipose tissues (p < 0.05). This occurred in conjunction with increases in PPARγ protein expression. Conversely, the protein expression of C/EBPα was reduced in the −20% group (p < 0.05). Moreover, the −20% group had increased/decreased phosphorylation of AMPKα/mTOR, respectively (p < 0.05). As for the colonic gut microbiota, a 20% reduction in the protein level led to increased Lachnospiraceae XPB1014 group abundance at the genus level (p < 0.01). Collectively, these results indicated that a 20% protein reduction could modulate lipid metabolism and alter the colonic microbiota of Shaziling pigs, an approach which might be translated into a treatment for obesity.

Effects of Long-Term Low-Protein Diets Supplemented with Sodium Dichloroacetate and Glucose on Metabolic Biomarkers and Intestinal Microbiota of Finishing Pigs

The objective of this study was to evaluate the effects of low-protein (LP) diets supplemented with sodium dichloroacetate (DCA) and glucose (GLUC) on metabolic markers and intestinal microbiota of finishing pigs. A total of 80 crossbred growing barrows were allocated randomly to one of the five treatments, including the normal protein level diet (CON), the LP diets, LP with 120 mg/kg DCA (LP + DCA) or 1.8% glucose (LP + GLUC), and LP with 120 mg/kg DCA and 1.8% glucose (LP + DCA + GLUC). The LP diet increased the plasma HDL, triglyceride, and cholesterol concentrations and reduced the bile acid, urea nitrogen, albumin, and total protein concentrations compared to the CON diet (p < 0.05). The LP + DCA + GLUC diet reduced the plasma VLDL, triglyceride, and cholesterol concentrations and increased the bile acid concentration compared with the LP diet (p < 0.05). Pigs fed the LP + DCA and LP + GLUC diets showed reduced 3-Hydroxy-3-Methylglutaryl-CoA Reductase content and increased Cytochrome P450 Family 7 Subfamily A Member 1 activity of liver compared that of the CON diet (p < 0.05). Moreover, the LP diets with or without DCA and GLUC supplementation increased the relative abundance of colonic microbiota related to carbohydrate fermentation in finishing pigs. In conclusion, 120 mg/kg DCA or 1.8% GLUC supplementation in an LP diet modulated the hepatic lipid metabolism of pigs, while the DCA along with GLUC supplementation likely improved the lipid metabolism by stimulating bile acid secretion.

Effects of Yeast Culture Supplementation in Wheat-Rice-Based Diet on Growth Performance, Meat Quality, and Gut Microbiota of Growing-Finishing Pigs

The aim of this study was to investigate the effects of yeast culture (Saccharomyces cerevisiae) supplementation on the growth performance, meat quality, gut health, and microbiota community of growing−finishing pigs. A total of 45 growing−finishing pigs were randomly allocated to three treatments: a corn−soybean-based diet (CON, n = 15), a wheat−rice-based diet (GRA, n = 15), and GRA supplemented with 500 mg/kg yeast culture (YC, n = 15). The results show that compared to the CON group, the GRA group exhibited no significant differences in feed intake, daily gain, or feed conversion ratio, but had significantly reduced feed cost per kilogram BW gain of the finishing pigs (p < 0.05). Compared to that of the CON group, the GRA and YC groups showed an increase in the dressing percentage (p < 0.1). The meat color redness of the YC group increased (p < 0.1), whereas the b* value at 24 h decreased (p < 0.1). Meanwhile, the addition of YC significantly increased total superoxide dismutase activity on day 30 and catalase activity on day 60 (p < 0.05), and decreased serum urea nitrogen content on day 60 (p < 0.05). Furthermore, YC supplementation increased the gene expression of the duodenal anti-inflammatory factor IL-10 (p < 0.05), while it significantly decreased the gene expression of the ileal pro-inflammatory factor IL-8 (p < 0.05). The intestinal microbial identification results show that compared to the CON group, the YC group showed an increase in the relative abundances of Lactobacillus, Streptococcus, and Clostridium in the colon, and a decrease in the relative abundances of Bacteroidea, Clostridae, and Prevotella in the cecum. In conclusion, the growth performance of pigs on a wheat−rice-based diet was similar to that of pigs on a corn−soybean-based diet. Supplementation of 0.5% YC in the wheat−rice-based diet could improve the dressing percentage and meat color of growing−finishing pigs, which might be due to the increase in nitrogen utility and antioxidant capacity, and the improvement of the immune system and changes in microbiota communities.

Influences of Dietary Vitamin E, Selenium-Enriched Yeast, and Soy Isoflavone Supplementation on Growth Performance, Antioxidant Capacity, Carcass Traits, Meat Quality and Gut Microbiota in Finishing Pigs

This study investigated the effects of dietary compound antioxidants on growth performance, antioxidant capacity, carcass traits, meat quality, and gut microbiota in finishing pigs. A total of 36 barrows were randomly assigned to 2 treatments with 6 replicates. The pigs were fed with a basal diet (control) or the basal diet supplemented with 200 mg/kg vitamin E, 0.3 mg/kg selenium-enriched yeast, and 20 mg/kg soy isoflavone. Dietary compound antioxidants decreased the average daily feed intake (ADFI) and feed to gain ratio (F/G) at d 14−28 in finishing pigs (p < 0.05). The plasma total protein, urea nitrogen, triglyceride, and malondialdehyde (MDA) concentrations were decreased while the plasma glutathione (GSH) to glutathione oxidized (GSSG) ratio (GSH/GSSG) was increased by compound antioxidants (p < 0.05). Dietary compound antioxidants increased loin area and b* value at 45 min, decreased backfat thickness at last rib, and drip loss at 48 h (p < 0.05). The relative abundance of colonic Peptococcus at the genus level was increased and ileal Turicibacter_sp_H121 abundance at the species level was decreased by dietary compound antioxidants. Spearman analysis showed a significant negative correlation between the relative abundance of colonic Peptococcus and plasma MDA concentration and meat drip loss at 48 h. Collectively, dietary supplementation with compound antioxidants of vitamin E, selenium-enrich yeast, and soy isoflavone could improve feed efficiency and antioxidant capacity, and modify the backfat thickness and meat quality through modulation of the gut microbiota community.