Objective: The purpose of this study was to investigate the effects of different doses of Sophora alopecuroides (SA) on the rumen fermentation and microbial diversity of sheep.Methods: A total of 32 healthy Dumont crossbred male lambs weighing 25.73 ± 2.17 kg were randomly assigned to 4 treatment groups with 8 replicates each: a control group (CG) fed a basal diet with a concentrate-to-forage ratio of 7:3 and three experimental groups - the 0.1% group(TG1), 0.3% group (TG2), and 0.5% group (TG3), which were fed the same basal diet but supplemented with increasing doses of SA.Results: (1) Increasing the SA dose led to a significant linear increase (p-< 0.05) in acetate, propionate, butyrate, and total volatile fatty acid (TVFA) concentrations in the rumen, as well as a significant quadratic effect (p-< 0.05) on the propionate concentration. In contrast, there was a significant linear decrease (p-< 0.05) in the NH₃-N concentration in the rumen. (2) At the level of rumen bacterial phyla, the abundance of Bacteroidetes in the rumen increased, and that of Firmicutes decreased (p = 0.08). At the genus level, the rumen abundances of Ruminococcus and Phocaeicola of sheep in the three experimental groups were significantly higher than in the control group (p-< 0.05), and the abundances of Clostridiales and Candidatus-Hepatincola were significantly increased in the 0.1% and 0.3% groups (p < 0.05). (3) Regarding rumen anaerobic fungi, the differences between the control group and experimental groups at the phylum level and genus level were not significant (p > 0.05), but the relative abundances of Neocallimastigomycota and Piromyces in the 0.1% group were significantly higher than that in the control group.Conclusion: SA addition to a high grain diet could increase the VFA concentration and pH in the sheep rumen, reduce the NH₃-N concentration in the rumen and improve rumen fermentation function. Although there was no significant change in rumen bacterial or fungal diversity, SA addition increased the rumen abundances of Bacteroidetes, Ruminococcus, Phocaeicola, Clostridiales, Neocallimastigomycota and Piromyces, decreased the rumen abundance of Firmicutes, and had a positive effect on the rumen microbiota to improve sheep health.

The purpose of this study was to determine the effects of Sophora alopecuroides (SA) on liver function, liver inflammatory factor levels, antioxidant indexes and transcriptome in sheep. Twenty-four 3-month-old healthy Dumont hybrid lambs weighing 25.73 ± 2.17 kg were randomly divided into three groups: C1 (the control group), fed a concentrate-to-forage ratio of 50:50; H2 (the high-concentration group), fed a concentrate-to-forage ratio of 70:30; and S3 (the SA group), fed a concentrate-to-forage ratio of 70:30 + 0.1% SA. The results showed that the rumen pH values of the C1 and S3 groups were significant or significantly higher than that of the H2 group (p < 0.05 or p < 0.01). The serum ALT, AST and LDH activities and the LPS and LBP concentrations in the sheep serum and liver in the H2 group were significantly or extremely significantly higher than those in the C1 and S3 groups (p < 0.01), and the IL-10 content and SOD, GPX-P_X and T-AOC activities showed the opposite trend (p < 0.05 or p < 0.01). KEGG enrichment analysis showed that the differentially expressed genes were significantly enriched in the ECM–receptor interaction and focal adhesion pathways, which are closely related to immune and antioxidant functions (p-adjust < 0.1). In summary, SA could improve the immune and antioxidant functions of lamb livers under high-concentrate conditions and regulate the mechanism of damage on sheep livers, which is caused by high-concentrate diets and through the expression of related genes in the ECM/FAs pathway.

Feeding HC diets has been found to induce metabolic dysregulation in the colon. However, the mechanisms by which changes in colonic flora and metabolites damage the colonic epithelium are poorly studied. Therefore, the present experiment used a multi-omics technique to investigate the mechanism of colonic injury induced by high-concentrate diets in lambs. Twelve male Dumont lambs were randomly split into two groups: a low-concentrate diet (LC = concentrate/forage = 30:70) group and a high-concentrate diet (HC = concentrate/forage = 70:30) group. The results showed that the HC group presented significantly increased lipopolysaccharide (LPS) concentrations in the colonic epithelium and significantly decreased serum total cholesterol (TC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels (p < 0.05), which led to cavities and inflammatory cell infiltration in the colonic epithelium. The HC group had significantly lower pH and less VFAs in colon contents, as well as a significantly increased abundance of bacteria of the genera [Eubacterium]_coprostanoligenes_group, Rikenellaceae_RC9_gut_group, Treponema, Clostridia_UCG-014, Alistipes, Ruminococcus, Christensenellaceae_R-7_group, UCG-002, Bacteroidales_RF16_group and Lachnospiraceae_AC2044_group compared to the LC diet group. These microorganisms significantly increased the level of metabolites of cholic acid, chenodeoxycholic acid, LysoPA (P-16:0/0:0), methapyrilene, and fusaric acid. A transcriptome analysis showed that cytokine–cytokine receptor interaction, glutathione metabolism, and the peroxisome signaling pathway were downregulated in the colon epithelium of the lambs fed the HC diet. Therefore, the HC diet caused epithelial inflammation and oxidative damage by affecting the interaction between the microbial flora of the colon and metabolites and the host epithelium, which eventually disrupted colon homeostasis and had a negative impact on sheep health.

Appropriate soluble carbohydrate (SCHO)-to-NDF ratios in the diet are essential for rumen health. The effects of different SCHO-to-NDF ratios (1.0, 1.5, and 2.0) on rumen barrier function and inflammation in Dumont lambs (n = 18, 6 replicates per treatment) was investigated. The SCHO:NDF ratio was altered by replacing the forage (Leynus chinensis) with corn grain. With an increase in the proportion of SCHO, the final body weight (FBW), average daily gain (ADG), soluble carbohydrate intake (SCHOI), and LPS level increased; and the neutral detergent fiber intake (NDFI), ruminal papillae height, papillae area, and pH decreased (p < 0.05, p_lin < 0.05). The medium CHO:NDF group had increased claudin-1 mRNA (p < 0.05, p_lin = 0.005, p_quad = 0.003) and protein (p < 0.05, p_quad < 0.001) levels; the high CHO:NDF group had increased occludin mRNA and protein (p < 0.05, p_lin = 0.001) levels. The level of the anti-inflammatory cytokine IL-10 was significantly greater in the medium CHO:NDF group than in the high CHO:NDF group (p < 0.05, p_quad < 0.001). With an increase in the ratio of SCHO, the mRNA level and concentration of the proinflammatory cytokines IL-1β, IL-6, and TNF-α linearly increased (p < 0.05, p_lin < 0.05), and those in the high CHO:NDF group were significantly greater than those in the low CHO:NDF group. The levels of phosphorylated p65 (p_lin = 0.003), IκB-α (p_lin < 0.001), and JNK (p_lin = 0.001) increased linearly, and those in the high CHO:NDF group were significantly greater than those in the other two groups (p < 0.05). Therefore, when the SCHO-to-NDF ratio was increased to 1.5, the rumen epithelium was not affected, but when the ratio was increased to 2.0, NF-κB and MAPK were activated in the rumen epithelium, leading to impaired barrier function and inflammation. The suitable NFC:NDF ratio for the short-term fattening of Dumont lambs was found to be 1.50.

This study investigated the effects of replacing part of the soybean meal in the diet of Dumont lambs with urea, rapeseed meal, and cottonseed meal on their growth performance and rumen fermentation and combined rumen microbial metagenomics and metabolomics to explain the reasons for the changes in phenotypic data. Twenty-four healthy male Dumont lambs were divided into four groups: soybean meal group (T1, control group), group with 1.5% urea replacing 6.4% soybean meal (T2), group with 1% urea replacing 4.3% soybean meal (T3), and group with 1% urea + 6.6% cottonseed meal +5% rapeseed meal replacing all soybean meal (19%) (T4), following the principle of equal energy and nitrogen. Urea, rapeseed meal, and cottonseed meal have different degradation rates in the rumen, primarily stimulating arginine biosynthesis, sulphur metabolism, and carbon fixation in photosynthetic organisms through Prevotella genus mediation, thereby influencing the accumulation of metabolites such as 9,10-DiHOME, DG (PGJ2/a-15:0/0:0), isonicotinate and taxifolin, affecting rumen fermentation. Compared with the T1 group, the T2 group showed significantly increased ammonia nitrogen (NH₃-N) and microbial protein (MCP) content (p < 0.01) and improved fructose and mannose metabolic capacity (p < 0.05). The T3 group showed a significant increase in total volatile fatty acids (TVFA) and MCP content (p < 0.01), which facilitated the absorption of subsequent nutrients. In the T4 group, different degradation rates of nitrogen resources and rapeseed meal + cottonseed meal contained abundant and complementary amino acids, which improved rumen fermentation, enhanced rumen microbial and metabolite diversity, and optimized the synergistic metabolic efficiency of carbon, nitrogen and sulphur. However, the specific mechanisms of post-rumen metabolism and absorption require further investigation.