Liu Renping, Li Peiyao, Fan Chen, Wang Shanshan, Liu Zhiqiang, Zhao Guodong, Yang Kailun
College of Animal Science, Xinjiang Agricultural University, Urumqi, China.
Xinjiang Shangpin Meiyang Technology Co., Ltd., Changji, China.
Front Microbiol. 2025 Jun 25;16:1606437. doi: 10.3389/fmicb.2025.1606437. eCollection 2025.
Citrulline (Cit), a non-essential amino acid, is characterized by its unique extrahepatic metabolism, which significantly enhances the bioavailability of arginine metabolism in tissues. This study investigated the impact of -Cit supplementation on ruminal microbiota composition, plasma metabolites, reproductive hormones, and antioxidant capacity in Hu ewes. Sixty non-pregnant Hu ewes, similar in age and parity, with an average body weight of 47 ± 5.05 kg, were randomly assigned to either a Control group or Experimental group. The Control group received a basal diet, while the Experimental group was supplemented with 10 g/d of -Cit in addition to the basal diet for 65 days. Compared to the Control group, the Experimental group exhibited a significantly higher estrus rate. Plasma estradiol (E) levels were significantly reduced ( < 0.01), while luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations showed significant increases ( < 0.05). Testosterone (T) content was also significantly elevated ( < 0.01). Plasma levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-PX), catalase (CAT), and total antioxidant capacity (T-AOC) were significantly higher in the experimental group, with highly significant differences ( < 0.01). The 16S rRNA sequencing analysis revealed that at the phylum level, the relative abundance of Bacteroidetes was decreased, while that of Firmicutes was increased in the experimental group. At the family level, the relative abundance of norank_o__Clostridia_UCG-014 was significantly increased. At the genus level, the relative abundance of Prevotellaceae_UCG-003 was significantly decreased. The main enriched pathways in the CON group were identified as Lipoic acid metabolism and Nicotinate and nicotinamide metabolism. The main enriched pathways in the experimental group were identified as Prion diseases, Chlorocyclohexane and chlorobenzene degradation, Chloroalkane and chloroalkene degradation, Biofilm formation-, and Phosphotransferase system (PTS). LC-MS analysis indicated significant upregulation of pathways such as drug metabolism by other enzymes, folate biosynthesis, and valine, leucine, and isoleucine biosynthesis, whereas oxidative phosphorylation and propanoate metabolism were significantly downregulated. These results demonstrate that -Cit supplementation in the diet modulates the ruminal microbiota of Hu ewes, optimizing volatile fatty acid (VFA) proportions, enhancing carbohydrate metabolism, improving xenobiotic degradation capacity, stimulating the synthesis and release of reproductive hormones. Ultimately, these coordinated effects led to a synergistic increase in estrus and conception rates.
瓜氨酸（Cit）是一种非必需氨基酸，其特点是具有独特的肝外代谢途径，这显著提高了组织中精氨酸代谢的生物利用度。本研究调查了添加瓜氨酸对湖羊瘤胃微生物群组成、血浆代谢物、生殖激素和抗氧化能力的影响。60只年龄和胎次相近、平均体重为47±5.05千克的未怀孕湖羊被随机分为对照组或实验组。对照组接受基础日粮，实验组在基础日粮之外每天补充10克瓜氨酸，持续65天。与对照组相比，实验组的发情率显著更高。血浆雌二醇（E）水平显著降低（P<0.01），而促黄体生成素（LH）和促卵泡生成素（FSH）浓度显著升高（P<0.05）。睾酮（T）含量也显著升高（P<0.01）。实验组血浆中超氧化物歧化酶（SOD）、丙二醛（MDA）、谷胱甘肽过氧化物酶（GSH-PX）、过氧化氢酶（CAT）和总抗氧化能力（T-AOC）水平显著更高，差异极显著（P<0.01）。16S rRNA测序分析表明，在门水平上，实验组拟杆菌门的相对丰度降低，而厚壁菌门的相对丰度增加。在科水平上，无分类单元的梭菌纲UCG-014的相对丰度显著增加。在属水平上，普雷沃氏菌科UCG-003的相对丰度显著降低。对照组主要富集的途径被确定为硫辛酸代谢和烟酸及烟酰胺代谢。实验组主要富集的途径被确定为朊病毒病、氯环己烷和氯苯降解、氯代烷烃和氯代烯烃降解、生物膜形成以及磷酸转移酶系统（PTS）。液相色谱-质谱分析表明，其他酶的药物代谢、叶酸生物合成以及缬氨酸、亮氨酸和异亮氨酸生物合成等途径显著上调，而氧化磷酸化和丙酸代谢则显著下调。这些结果表明，日粮中添加瓜氨酸可调节湖羊的瘤胃微生物群，优化挥发性脂肪酸（VFA）比例，增强碳水化合物代谢，提高外源化合物降解能力，刺激生殖激素的合成和释放。最终这些协同作用导致发情率和受孕率协同提高。
