Effects of fermented sweet potato residue on nutrient digestibility, meat quality, and intestinal microbes in broilers.

This study aimed to investigate the effects of different proportions of dietary fermented sweet potato residue (FSPR) supplementation as a substitute for corn on the nutrient digestibility, meat quality, and intestinal microbes of yellow-feathered broilers. Experiment 1 (force-feeding) evaluated the nutrient composition and digestibility of mixtures with different proportions of sweet potato residue (70%, 80%, 90%, and 100%) before and after fermentation. In Experiment 2 (metabolic growth), a total of 420 one-day-old yellow-feathered broilers were randomly allocated to 4 groups and fed corn-soybean meal-based diets with 0, 5%, 8%, and 10% FSPR as a substitute for corn. The force-feeding and metabolic growth experiments were performed for 9 and 70 d, respectively. The treatment of 70% sweet potato residue (after fermentation) had the highest levels of crude protein, ether extract, and crude fiber and improved the digestibility of crude protein and amino acids (P < 0.05). Although dietary FSPR supplementation at different levels had no significant effect on growth performance and intestinal morphology, it improved slaughter rate, half-chamber rate, full clearance rate, and meat color, as well as reduced cooking loss in the breast and thigh muscles (P < 0.05). Dietary supplementation with 8% and 10% FSPR increased the serum immunoglobulin M and immunoglobulin G levels in broilers (P < 0.05). Furthermore, 10% FSPR increased the Shannon index and Ruminococcaceae_UCG-014, Ruminococcaceae_UCG-010 and Romboutsia abundances and decreased Sutterella and Megamonas abundances (P < 0.05). Spearman's correlation analysis showed that meat color was positively correlated with Ruminococcaceae_UCG-014 (P < 0.05) and negatively correlated with Megamonas (P < 0.05). Collectively, 70% sweet potato residue (after fermentation) had the best nutritional value and nutrient digestibility. Dietary supplementation with 8% to 10% FSPR as a substitute for corn can improve the slaughter performance, meat quality, and intestinal microbe profiles of broilers. Our findings suggest that FSPR has the potential to be used as a substitute for corn-soybean meals to improve the meat quality and intestinal health of broilers.

d-Aspartate in Low-Protein Diets Improves the Pork Quality by Regulating Energy and Lipid Metabolism via the Gut Microbes.

d-Aspartate is critical in maintaining hormone secretion and reproductive development in mammals. This study investigated the mechanism of different d-aspartate levels (0, 0.005, 0.05, and 0.5% d-aspartate) in low-protein diets on growth performance and meat quality by mediating the gut microbiota alteration in pigs. We found that adding 0.005% d-aspartate to a low-protein diet could dramatically improve the growth performance during the weaned and growing periods. Dietary d-aspartate with different levels markedly increased the back fat, and 0.5% d-aspartate significantly increased the redness in 24 h and reduced the shear force of the longissimus dorsi (LD) muscle. Moreover, d-aspartate treatments decreased the mRNA expression of MyHC II a and MyHC IIx in the LD muscle. The protein expression of MyH1, MyH7, TFAM, FOXO1, CAR, UCP2, and p-AMPK was upregulated by 0.005% d-aspartate. Additionally, the abundance of Alistipes, Akkermansia, and the [Eubacterium]_coprostanoligenes_group in the intestinal chyme of pigs was significantly decreased by d-aspartate treatments at the genus level, which was also accompanied by a significant decrease in acetate content. These differential microorganisms were significantly correlated with meat quality characteristics. These results indicated that d-aspartate in low-protein diets could improve the growth performance and meat quality in pigs by regulating energy and lipid metabolism via the alteration of gut microbiota.

D-Galactose Induces Chronic Oxidative Stress and Alters Gut Microbiota in Weaned Piglets.

Oxidative stress commonly occurs in pig production, which can severely damage the intestinal function of weaned piglets. This study was conducted to investigate the effects of D-galactose with different levels used to induce chronic oxidative stress on growth performance, intestinal morphology and gut microbiota in weaned piglets. The results showed that addition of 10 and 20 g/kg BW D-galactose reduced average daily gain and average daily feed intake from the first to the third week. 10 g/kg BW D-galactose increased the concentration of serum MDA at the second and third week. 10 g/kg BW D-galactose significantly influenced the jejunal and ileal expressions of GPx1, CAT1, and MnSOD. The results of 16S rRNA sequencing showed that compared with the control, 10 and 20 g/kg BW D-galactose significantly decreased the relative abundance of Tenericutes, Erysipelotrichia, Erysipelotrichales, and Erysipelotrichaceae, while increased the relative abundance of Negativicutes, Selenomonnadales, and Veillonellaceae. The results indicated that treatment with 10 g/kg BW/day D-galactose for 3 weeks could induce chronic oxidative stress, reduce the growth performance and alter gut microbiota in weaned piglets.