High-Fiber Diet Supplemented with N-Carbamylglutamate Modulates Uterine Microbiota, Metabolites, and Transcriptome to Improve Reproductive Efficiency in Sows

Uterine microbiome homeostasis and antioxidant capacity are critical for sow fertility. While high-fiber diets and N-carbamylglutamate (NCG) individually enhance sow fertility, their synergistic effects on the antioxidant status, microbiota, metabolites, and transcriptome remain unclear. Here, sows were assigned to the low-fiber (3.73%) or high-fiber (7.46% crude fiber) group, each without or with 0.05% NCG, throughout the 114-day gestation. Sex hormones and antioxidants in serum were detected. Multi-omics approaches were employed to investigate the impact of a high-fiber diet supplemented with NCG (H + N) on uterine microbiota, metabolites, and gene expression profiles. The study revealed that H + N significantly increased total antioxidant capacity (T-AOC) level in serum. Metagenomic analysis revealed an increased abundance of <i>Clostridium disporicum</i> in the uterine microbiota. Plasma metabolomics identified hydroxylysine as a key metabolite mediating this effect, and this metabolite was positively correlated with elevated abundance of <i>Clostridium disporicum</i>. Subsequent transcriptomic profiling revealed activation of the PI3K-Akt signaling pathway, closely linked to improved T-AOC level. Overall, these findings demonstrated that H + N could modulate the uterine microbiota (specifically <i>Clostridium disporicum</i>), increase hydroxylysine production, and activate the PI3K-Akt signaling pathway. These effects further enhanced hormonal activity and antioxidant capacity, ultimately improving sow reproductive efficiency.