Study on the effect of N-carbamylglutamate (NCG) on reproductive performance and regulation mechanism of primary lake sheep

Objective To investigate the effects of dietary supplementation with 0.11% N-carbamylglutamate (NCG) during early pregnancy (0–90 days) on reproductive performance and fetal development, as well as to elucidate the underlying molecular mechanisms in primiparous Hu sheep. Methods Twelve 10-month-old sexually mature primiparous Hu sheep meeting the mating criteria were randomly assigned to two groups. The control group was fed a basal diet, while the NCG group received the basal diet supplemented with 0.11% NCG, with both feeding regimens maintained for 90 days. Through measurements of uterine and fetal growth indices, maternal plasma biochemical parameters, and amino acid levels, as well as assessments of cotyledon indices, observations of cotyledon morphology and histological structure, and transcriptomic sequencing of maternal placental tissue, the mechanism by which NCG influences placental function and fetal growth and development in pregnant ewes was investigated.. Results Dietary supplementation with NCG significantly increased fetal number, total fetal weight, corpus luteum count, fetal-to-luteum ratio, plasma levels of NO, iNOS, and concentrations of several amino acids ( P  < 0.05). In ewes' uteri, the average uterine weight, number of uterine glands, total cotyledon weight, and average weight per cotyledon were significantly increased ( P  < 0.05), whereas uterine mucosal thickness was markedly decreased. The q-PCR results for differentially expressed genes were consistent with those of transcriptomic analysis, showing significant changes in the expression levels of certain differentially expressed genes in maternal placental tissues. These changes regulated pathways such as VEGF, IGF, PI3K-AKT and MAPK, which are involved in angiogenesis, energy supply and metabolism, and somatic growth and development.. Conclusion Dietary supplementation with NCG during early pregnancy can significantly improve the reproductive performance of primiparous Hu sheep, optimize the intrauterine environment and nutrient supply, and thereby facilitate pregnancy maintenance and fetal development. The underlying mechanism may involve promoting endogenous arginine synthesis in ewes, increasing plasma levels of NO, arginine, and certain amino acids, which collectively validate the positive effects of NCG on the reproductive performance and growth of Hu sheep during early pregnancy at the molecular level.