Bovine rotavirus (BRV) is a major pathogen causing diarrhea in neonatal dairy calves, yet its impact on the gut microbiome and host metabolism remains incompletely understood. This study integrated 16S rRNA gene sequencing and untargeted metabolomics to characterize the fecal microbial and metabolic profiles of BRV-infected diarrheic calves compared to healthy controls. Fecal samples were collected from 16 Holstein calves (<30 days old), equally divided into a BRV-infected group (confirmed by RT-qPCR) and a healthy control group. Alpha diversity analysis revealed a significant reduction in microbial richness (Chao1, p = 0.012) in the BRV group. Beta diversity (Jaccard distance) showed distinct clustering between groups (PERMANOVA, p < 0.05). Linear discriminant analysis effect size (LEfSe) identified a significant enrichment of Escherichia (Proteobacteria) and Enterococcus (Firmicutes) in BRV calves, whereas healthy controls were enriched in Blautia and Faecalibacterium (both Firmicutes, with Faecalibacterium also commonly associated with healthy gut communities). Metabolomic analysis via UHPLC-MS/MS demonstrated a clear separation of metabolic profiles. BRV infection was associated with significant alterations in lipid metabolism pathways, notably elevated levels of lysophosphatidylcholines (LPCs) and lysophosphatidylethanolamines (LPEs). Integrated Spearman correlation analysis revealed extensive and significant associations (|ρ| > 0.6, FDR-adjusted p < 0.05) between differential bacterial genera (e.g., Enterococcus, Escherichia) and differential metabolites (e.g., glycerolipids, amino acid derivatives), suggesting a close linkage between gut microbial dysbiosis and metabolic remodeling during BRV infection. These findings provide a multi-omics perspective on the interplay between the gut microbiota and host metabolism in BRV-induced diarrhea, offering potential insights for developing microbiota-based diagnostic or therapeutic strategies.

Bovine viral diarrhea virus (BVDV) is a viral pathogen that may cause reproductive disorders, health, and performance. BVDV serotypes have undergone dynami

Grazing is a free-range farming model commonly practiced in low-external-input agricultural systems. The widespread use of veterinary antibiotics in livestock farming has led to significant environmental accumulation of antibiotic residues and antibiotic resistance genes (ARGs), posing global health risks. This study investigated the antibiotic residues, bacterial community, ARG profiles, and mobile genetic elements (MGEs) in cattle feces from three provinces in western China (Ningxia, Xinjiang, and Inner Mongolia) under grazing modes. The HPLC-MS detection showed that the concentration of tetracycline antibiotics was the highest in all three provinces. Correlation analysis revealed a significant negative correlation between antibiotic residues and the diversity and population abundance of intestinal microbiota. However, the abundance of ARGs was directly proportional to antibiotic residues. Then, the Sankey analysis revealed that the ARGs in the cattle fecal samples were concentrated in 15 human pathogenic bacteria (HPB) species, with 9 of these species harboring multiple drug resistance genes. Metagenomic sequencing revealed that carbapenemase-resistant genes (bla_KPC and bla_VIM) were also present in considerable abundance, accounting for about 10% of the total ARGs detected in three provinces. Notably, Klebsiella pneumoniae strains carrying bla_CTX-M-55 were detected, which had a possibility of IncFII plasmids harboring transposons and IS19, indicating the risk of horizontal transfer of ARGs. This study significantly advances the understanding of the impact of antibiotic residues on the fecal microbiota composition and ARG profiles in grazing cattle from northwestern China. Furthermore, it provides critical insights for the development of rational antibiotic usage strategies and comprehensive public health risk assessments.