Weaning is one of the most stressful periods in yak growth. However, the impact of weaning on microbial diversity, structure, and potential function of yak feces is not clear. In this study, 12 Xinjiang yaks aged 3, 4, 5, and 6 months old were selected to collect fresh feces before and after weaning. Through 16S rRNA and ITS high‐throughput sequencing, the dynamic distribution and potential function of yak fecal, bacterial, and fungal communities in each month were revealed. The study found that the richness of fungi had a significant impact on weaning. At the phylum level, Firmicutes, Bacteroidetes, Ascomycota, and Basidiomycota, and at the genus level, 5-7N15, Oscillospira, Roseburia, Dorea, Preussia, Neoascochyta, Naganishia, and Sporormiella were enriched in yak feces of different months old. The abundance and proportion of bacteria Firmicutes, Bacteroidetes, 5-7N15, and fungi Mucoromyceta changed significantly before and after weaning. With the increase of months, Verrucomicrobia and Akkermansia have shown a downward trend. Through the prediction and analysis of fecal microbial function, it was found that at the level of primary pathways, weaning has a significant impact on cellular processes, environmental information processing, genetic information processing, metabolism, and organismal systems. At the level of secondary metabolic pathways, weaning has a significant impact on cell motility, signal transduction, folding, sorting and degradation, translation, amino acid metabolism, glycan biosynthesis and metabolism, metabolism of terpenoids and polyketides, and xenobiotics biodegradation and metabolism. In addition, by analyzing the differences in functional pathways and microbial composition between sample groups of different months, it was found that the differences in functional pathways were related to the abundance differences of some microorganisms. In general, the changes in the composition and structure of yak fecal microflora may reflect the adaptability of the intestinal microbiota.

This experiment investigated the effects of rumen-protected leucine (RP-Leu) supplementation on growth performance, rumen fermentation parameters, and rumen microbiota of fattening sheep. Forty fattening sheep (19.03 ± 0.38 kg) were randomly divided into four groups. The four groups were fed the basal diet supplemented with RP-Leu at 0 (L-0), 0.5 (L-0.5), 1.0 (L-1.0), or 1.5 (L-1.5) g/d. The experimental period lasted 67 d. The results demonstrated that compared with the L-0 group, the L-1.0 and L-1.5 groups significantly increased the average daily gain (ADG) by 22.2% and 18.0%, respectively (p < 0.05), and reduced the feed-to-gain ratio (F:G ratio) by 20.0% and 13.4% (p < 0.05); the L-1.5 group significantly increased the concentrations of propionate and isovalerate (p < 0.05) and significantly decreased the acetate to propionate ratio (A:P) by 25.7% (p < 0.05); and the L-1.0 group significantly decreased the concentrations of free branched-chain amino acids (BCAAs) in rumen (p < 0.05). A microbiota analysis showed that RP-Leu enriched the abundance of fiber-degrading bacteria. A correlation analysis showed that acetic acid and A:P were positively correlated with norank_f_F082 and norank_f_UCG-011 (p < 0.05). Phenylalanine, isoleucine, valine, and leucine were negatively correlated with norank_o_Bacteroidales (p < 0.05). In conclusion, RP-Leu improved the growth performance of fattening sheep by changing the rumen fermentation parameters and patterns; the optimal supplementation level is 1.0 g/d.

This study evaluated the effects of sea buckthorn polysaccharides (SBP) on rumen fermentation in Hu sheep through in vitro fermentation. A single-factor randomized design was employed with four treatment groups in which SBP was added to a basal diet at 0, 1%, 2% and 3% of the total ration dry matter (DM). Based on gas production, degradation rates, and fermentation parameters, the control group and the 2% group were selected for 16S rDNA sequencing. The results showed that compared with the control group, the 2% SBP treatment significantly increased gas production rate (p < 0.05). Addition of 2% and 3% SBP significantly increased DM degradability (p < 0.05). SBP supplementation significantly increased fermentation fluid pH (p < 0.05) and altered volatile fatty acid profiles, increasing the acetate/propionate ratio as well as the concentrations of butyrate, isobutyrate and valerate. Compared with the control group, the addition of 2% SBP led to significant changes in the microbial composition of the in vitro rumen fermentation fluid. It significantly increased beneficial bacterial phyla and genera, such as Bacteroidetes, Rikenellaceae_RC9_gut_group and others, while reducing pathogenic bacteria (p < 0.05). Additionally, functional prediction revealed that the SBP group was significantly enriched in pathways related to carbohydrate metabolism, biosynthesis of amino acid, and biosynthesis of secondary metabolites (p < 0.05). In summary, adding 2% SBP to Hu sheep feed can improve the Rumen fermentation and microbial communities. However, higher doses did not yield additional benefits in these measured indicators.

Background: Diarrhea in suckling lambs is associated with gut microbiota dysbiosis, impaired intestinal barrier function, and enhanced inflammatory responses. However, the specific intestinal microbes and microbial metabolites linked to intestinal homeostasis in suckling lambs remain unclear. Results: In this study, diarrheic lambs showed significantly higher serum diamine oxidase (DAO) activity, D-lactate (D-LA), and pro-inflammatory cytokine levels than healthy lambs. We then compared gut microbial composition and metabolite profiles between healthy and diarrheic suckling lambs. Diarrheal lambs exhibited gut microbiota dysbiosis, characterized by an elevated Bacillota (syn. Firmicutes)/Bacteroidota (syn. Bacteroidetes) ratio, reduced abundance of beneficial commensals including Phocaeicola vulgatus and Bacteroides fragilis , and proliferation of the opportunistic pathogen Clostridium perfringens . Metabolomic analysis showed that, in diarrheic lambs, the tryptophan metabolism pathway was reduced with lower levels of indole-3-carboxaldehyde (IAld) and 5-hydroxyindole-3-acetic acid (5-HIAA) than in healthy lambs. Fecal microbiota transplantation experiments showed that transplantation of microbiota from diarrheic lambs partially recapitulated the donor-associated microbial, metabolic, and inflammatory phenotypes in recipient mice. Finally, functional validation using a dextran sulfate sodium (DSS)-induced colitis model revealed that supplementation with IAld and 5-HIAA significantly alleviated DSS-induced intestinal inflammation and barrier damage, accompanied by downregulated expression of genes related to the Tlr4-Myd88-Nfκb signaling pathway. Conclusions: Our findings indicate that the gut microbiota-derived tryptophan metabolites IAld and 5-HIAA alleviated inflammation and improved intestinal epithelial barrier function by enhancing tight junction integrity, while also reducing the expression of Tlr4/Myd88/Nfκb pathway-related inflammatory signaling molecules.

Introduction: As the primary nutritional source for grazing livestock, natural forage directly influences changes in physiological status and rumen microbial community structure owing to seasonal variations in its nutritional composition. However, the physiological and rumen microbial community adaptations of Chinese Altay sheep in response to seasonal variations in forage nutrition remain unclear. Methods: Therefore, this study systematically evaluated the effects of seasonal dynamics in forage nutrition on growth performance, nutrient digestibility, blood parameters, rumen fermentation characteristics, and rumen microbiota in grazing Chinese Altay sheep. A total of 18 grazing Altay growing ewes with similar body weight, age, and good health condition were selected for the experiment. During four typical seasons (spring green-up, summer lush, autumn withering, and winter dormancy), Altay sheep were administered C ₃₂ slow-release capsules, with concurrent collection of forage, feces, blood, and rumen content samples. Results: The results indicated that the nutrient content of forages was abundant in summer and autumn, leading to high feed intake by the Altay sheep. This enabled the animals to promote weight gain through enhanced nutrient digestibility and rumen fermentation efficiency. Blood biochemical parameters of the Altay sheep varied in response to seasonal changes and forage nutrient availability. The results demonstrated that during summer, grazing Altay sheep exhibited a decline in antioxidant capacity, as well as reduced concentrations of Immunoglobulin A (IgA), Immunoglobulin G (IgG), and Immunoglobulin M (IgM). In autumn, significant enrichment of Bacillota and NK4A214_group was observed in the rumen of grazing sheep, which contributed to enhanced nutrient acquisition and thereby promoted fat deposition. In winter, Rikenellaceae_RC9_gut_group and Prevotellaceae_UCG-003 were significantly enriched in the rumen of grazing sheep, facilitating fiber decomposition and the production of volatile fatty acids (VFAs). Discussion and conclusion: This microbial adaptation helped the animals cope with nutrient scarcity by meeting their nutritional requirements. In conclusion, Altay sheep adapted to seasonal forage and environmental fluctuations through coordinated changes in feed intake, blood parameters, and rumen microbiota, thereby ensuring their survival.