Animals

The annual nitrogen loss from the livestock production sector poses a significant threat to the global natural environment. Therefore, it is urgent to focus on improving the nutrient utilization efficiency of ruminants and promoting the sustainable development of livestock production. Twelve 60-day-old Ganxi goats with similar body weights were selected and randomly assigned to two dietary treatment groups. The control group was fed only a basal diet, while the treatment group was supplemented with 32 mg/d of Swollenin. The experiment lasted for 30 days. At the end of the experimental period, the goats were euthanized, and their intestinal contents were collected, rapidly frozen, and stored at −80 °C for subsequent metagenomic and metabolomic analyses. In the Swollenin group, we observed changes in gut microbiota structure and significantly enhanced feed conversion efficiency compared to the control group. Notably, genera such as Bacteroides, Ruminococcus, and Bifidobacterium exhibited significantly higher abundance. Following Swollenin supplementation, the gene abundance associated with the secondary bile acid biosynthesis pathway in the intestinal tract of young goats was significantly higher. The levels of primary bile acids (BAs), including taurocholic acid, glycocholic acid, taurochenodeoxycholic acid, and glycochenodeoxycholic acid, were significantly lower, while the concentrations of secondary BAs such as ursodeoxycholic acid and deoxycholic acid were significantly higher. The abundance of nitrogen-fixing and nitrogen-assimilating genes in the gut of young goats in the Swollenin group was significantly higher. Furthermore, co-occurrence network analysis revealed a strong correlation between bile acid metabolism and nitrogen metabolism pathways. These results suggest that nutritional regulation may serve as a preventive strategy to optimize the symbiotic development of animals and their gut microbiota, ultimately improving nitrogen utilization.

Sex determination and differentiation in teleosts are governed by complex genetic regulatory networks that include evolutionarily conserved mechanisms. In this study, we investigated Boleophthalmus pectinirostris, a Gobiidae species lacking heterogametic sex chromosomes, using comparative gonadal transcriptome analysis to identify sex differentially expressed genes (DEGs). RNA sequencing of ovarian and testicular tissues identified 17,214 DEGs, including 14,302 upregulated in males and 2912 upregulated in females. These DEGs were primarily associated with male (e.g., dmrt1, amh, amhr2) or female (e.g., bmp15, gdf9, rspo1) sex determination and differentiation, steroidogenesis (e.g., hsd17b1, hsd3b1, cyp17a1), and meiosis (e.g., cyp26b1, aldh1a2, piwil2). Functional enrichment analysis revealed that male upregulated DEGs were involved in spermatogenesis pathways such as calcium signaling, while female upregulated DEGs were associated with oogenesis pathways including oocyte meiosis and progesterone-mediated oocyte maturation. Conserved regulators, notably dmrt1 and amh, were predicted to act as key hubs in protein–protein interaction networks, being primarily associated with reproductive processes and sex differentiation in B. pectinirostris. The amh gene produces two alternatively spliced isoforms that differ by a partial deletion in the second exon, both expressed in ovaries and testes. Collectively, this study provides the first comprehensive molecular framework of sex determination and differentiation in Gobiidae species, offering critical insights into the regulatory mechanisms of B. pectinirostris reproductive development.

This study aims to investigate the effects of dietary vitamin C supplementation on vitamin C synthesis, transport, and egg deposition in breeding geese. A total of 450 female and 90 male 221-day-old Yangzhou geese were randomly assigned to five treatment groups with six replicates each (15 females and 3 males per replicate). The control group received a basal diet, while the other four groups were fed diets supplemented with 100, 200, 300, and 400 mg/kg vitamin C over a 16-week feeding trial. The results showed that dietary vitamin C supplementation increased the vitamin C content in both serum and egg yolks and modulated the expression of key vitamin C-related genes. Specifically, the intestinal and ovarian sodium-dependent vitamin C transporters 1 and 2 (SVCT1/SVCT2) were upregulated, whereas hepatic and renal L-Gulonolactone oxidase (GLO) and SVCT1 were suppressed. These findings indicate that exogenous vitamin C enhances intestinal absorption, inhibits hepatic synthesis, and promotes yolk deposition, with 300 mg/kg emerging as an effective and practical supplementation level that provides a physiological basis for its application in poultry nutrition.