Castration is a prevalent and indispensable practice in sheep husbandry, aiding in enhancing meat quality, mitigating aggressive behavior, and managing unwanted reproduction. Nevertheless, the conventional surgical castration procedure poses several challenges, including heightened stress and pain, detrimental impacts on animal welfare, and diminished economic efficacy in farming operations. Consequently, immunocastration methods, serving as substitutes for surgical castration, are progressively finding application in livestock. The rumen, an essential and distinctive digestive and absorptive organ in ruminants, has been associated with enhanced meat quality and productive performance following castration in previous research studies, albeit fewer investigations have explored the potential impacts of GnRH immunization on the rumen’s internal milieu in sheep post-de-escalation. Hence, the present study delved into evaluating the impact of GnRH immunocastration on the rumen microbiome and metabolomics in male Xizang sheep. This was achieved through the establishment of a GnRH immunocastration animal model and the collection of rumen fluid for microbiological and comprehensive metabolomics investigations. The outcomes of this investigation unveiled that the impact of GnRH immunocastration on body weight gain was more pronounced during the achievement of the castration objective. In addition, the Firmicutes-to-Bacteroidota ratio in the immune male (IM) group exceeded that of the control group (EM), suggesting that GnRH immunodeficiency may enhance the digestion and absorption of feed in male Xizang sheep. At the taxonomic level, the elevated presence of Prevotella and Quinella bacteria in the IM group compared to the EM group indicated that castration influenced a segment of the rumen microbiota in male Xizang sheep, thereby bolstering the digestive and metabolic efficacy of the rumen concerning nutrient utilization, particularly in the breakdown and absorption of proteins, carbohydrates, and lipids, ultimately expediting the fattening process and weight gain in male Xizang sheep following castration. Moreover, analysis of ruminal fluid metabolomics revealed that GnRH immunization had notable impacts on certain metabolites in the ruminal fluid of male Xizang sheep, with metabolites like 5-hydroxyindole acetic acid and 3-hydroxyindole acetic acid showing significant downregulation in the IM group compared to the EM group, while niacin and tyramine exhibited significant upregulation. These findings indicate a profound influence of GnRH immunization on the maintenance of ruminal equilibrium and ruminal health (including the health of ruminal epithelial cells). This study validates that GnRH immunocastration not only achieves the objectives of castration but also enhances ruminal health in male Xizang sheep, thus laying a foundational theoretical basis for the application and dissemination of GnRH immunocastration technology.

Background/Objectives: The Xizang sheep is a unique breed of sheep in the highland regions of China that has gradually developed physiological characteristics adapted to the plate environment through long-term natural selection and artificial breeding. However, little is known about the molecular basis of metabolic adaptation to seasons in Xizang sheep. Methods: In this study, liver tissues from Xizang sheep in summer (SL) and autumn (AL) were selected for transcriptome sequencing to explore the metabolic adaptability of Xizang sheep to seasons. Results: The results showed that a total of 12,046 differentially expressed genes (DEGs) were identified, with 1123 genes significantly upregulated and 951 genes significantly downregulated in autumn. The top five pathways enriched for DEGs were Metabolic pathways, Phagosome, Valine, leucine and isoleucine degradation, Propanoate metabolism, and Fatty acid metabolism, which are involved in immune regulation, fat oxidation, and synthesis. The reduction in lipid synthesis, fatty acid oxidation, and fat breakdown metabolism promotes gluconeogenesis by inhibiting the Peroxisome proliferator-activated receptors (PPAR) and Phosphoinositide 3-kinase- Protein kinase B (PI3K-Akt) signaling pathways. Conclusions: This process helps to maintain the whole-body energy homeostasis of Xizang sheep, facilitating their adaptation to the seasonal changes in the extreme high-altitude environment. These findings provide foundational data for studying the molecular mechanisms of metabolic adaptation to seasons in ruminants.