Inhibition of the urease activity of ruminal microbiota is not only beneficial for increasing dietary and endogenic urea-N utilization efficiency in ruminants but also might be applicable for the preservation of nitrogen fertilizer in soil and treatment of gastrointestinal and urinary tract infections caused by ureolytic bacteria. To discover urease inhibitors to efficiently target ruminal microbiota, the identified ruminal microbial metagenomic urease gene was used to construct a homology model to virtually screen urease inhibitors from the ChemDiv database by molecular docking. The GMQE and QMEAN values of the homology model were 0.85 and −0.37, respectively, indicating a good model quality. The inhibition effect of the screened urease inhibitor for ruminal urea degradation was assessed by ruminal microbial fermentation in vitro. The toxic effect of the candidate inhibitor was performed using gut Caco-2 cells in vitro. The results showed that compound 3-[1-[(aminocarbonyl)amino]-5-(4-methoxyphenyl)-1H-pyrrol-2-yl] propanoic acid (ChemDiv_ID: 6238-0047, IC₅₀ = 65.86 μM) was found to be the most effective urease inhibitor among the candidate compounds. Compound 6238-0047 significantly lowered the amount of urea degradation and ammonia production in ruminal microbial fermentation. The 24 h degradation rate of compound 6238-0047 in ruminal microbial fermentation was 3.32%–16.00%. In addition, compound 6238-0047 (10–100 μM) had no significant adverse effect on the cell viability of Caco-2 cells. Molecular docking showed that compound 6238-0047 could interact with Asp359 in the active site and Cys318 in the flap region by the hydrogen bond and Pi-Alkyl interaction, respectively. Compound 6238-0047 could be used as a novel inhibitor for decreasing the urease activity of ruminal microbiota.

In this study, we examined the effect of xylooligosaccharide (XOS) supplementation on the growth performance, carcass characteristics, and meat quality of Hu lambs. In total, 60 Hu lambs (two months old and weighing 17.32 ± 0.81 kg) were randomly assigned to four treatment groups, each with three replicates and five lambs per replicate. The lambs were fed basal diets supplemented with 0, 1.5, 3, or 4.5 g/kg XOSs in a basal diet for 60 days, with the groups designated XOS0%, XOS1.5%, XOS3%, and XOS4.5%, respectively. The results revealed, compared to theXOS0% group, the XOS3% group presented a lower F:G during 31 to 45 d (p = 0.06). By the 60th day, the body length indices of groups XOS3% and XOS4.5% increased compared to the XOS0% group, with a significant increase observed in group XOS4.5% (p < 0.05). Additionally, the GR values of the XOS1.5%, XOS3%, and XOS4.5% groups increased significantly, and the rumen fluid pH values of the XOS3% and XOS4.5% groups increased significantly (p < 0.01). The crude fat content in the XOS1.5% and XOS4.5% groups were significantly lower (p < 0.05). The hardness, adhesiveness, elasticity, cohesiveness, and chewiness of the mutton in the XOS1.5%, XOS3%, and XOS4.5% groups were increased, although the differences were not statistically significant (p > 0.05). Correlation analysis indicates that there is a significant correlation between growth performance, carcass traits, and meat quality (p < 0.05). The factors influencing meat quality originate from the growth period and the slaughtering phase, which can be attributed to the effects of xylooligosaccharides. In conclusion, XOS had positive effects on the growth performance, carcass characteristics, and meat quality of Hu lambs. The comprehensive effect of group XOS3% was best. Considering the production cost, the 3 g/kg XOSs is identified as the optimal supplementation level for sheep.

Rumen microbial nitrogen metabolism is crucial for animal health, productivity, and environmental sustainability in ruminants. Natural products like biocha

This study investigated the variations in the fecal microbiota and serum metabolome of prolific Hu sheep across different gestational stages to understand their physiological relationships. Fecal and blood samples were collected from 24 multiparous ewes across four stages: non-pregnant and gestational days 55, 85, and 110. Fecal microbial communities were analyzed via 16S rRNA gene sequencing, and serum metabolic profiles were assessed using liquid chromatography–tandem mass spectrometry (LC-MS)-based untargeted metabolomics. Serum biochemical analysis showed that pregnant ewes had decreased urea concentrations (p < 0.05), an early-gestation peak in total cholesterol, and a mid-gestation peak in triglycerides (p < 0.05). Fecal microbiota analysis indicated higher alpha diversity during gestation than in the non-pregnant stage (p < 0.05), with Firmicutes as the dominant phylum and stage-specific variations in genera such as Negativibacillus and Monoglobus. Metabolomics analysis identified 68 differential metabolites primarily assigned to lipid, amino acid, and steroid hormone pathways. Procrustes and Spearman correlation analyses showed statistical concordance between the fecal microbial community structure and the serum metabolome. Specific genera, including UCG-005, Alistipes, and unclassified Lachnospiraceae, correlated positively with metabolites such as pregnanediol 3-O-glucuronide and specific sphingomyelins. In conclusion, the progression of pregnancy in Hu sheep is characterized by concurrent shifts in the fecal microbiota and serum metabolites. These concurrent variations correlate with host nitrogen reallocation and lipid parameters, providing baseline reference data for the nutritional management of gestating ewes. These results provide a useful reference for future studies investigating maternal physiology, nutrition, and microbiome dynamics in prolific sheep breeds.