Laboratory of Animal Genetic Breeding & Reproduction, Xinjiang Agricultural University, Xinjiang, China.
State Key Laboratory of Sheep Genetic Improvement and Healthy Breeding, Institute of Animal Husbandry and Veterinary Sciences, Xinjiang Academy of Agricultural and reclamation Sciences, Shihhotze, China.
Reprod Domest Anim. 2022 Jul;57(7):722-733. doi: 10.1111/rda.14111. Epub 2022 Mar 26.
With the aim of providing a theoretical basis for the application of L-citrulline (L-Cit) in animal husbandry, the effects of L-Cit on reproductive hormone levels, antioxidant capacity and semen quality of rams were studied by feeding them varying doses of L-Cit. A total of 32 rams were randomly divided into four groups with eight rams each. After all rams were trained to donate sperm normally, the control group was fed a basic diet, whereas the experimental groups I, II and III were provided with feed supplemented with 4, 8 and 12 g/d of L-Cit respectively. The experiment was conducted for 70 days, during which blood samples were collected from the jugular vein on days 0, 15, 30, 45 and 60, and semen samples were collected on days 0, 20, 40 and 60. In the same group, 100 µl of semen was used to test for quality, The rest of the semen sample and blood samples were centrifuged at 600 g for 15 min, and the supernatant and serum, respectively, were used to determine the levels reproductive hormones and antioxidant indices. Ram semen samples were also collected on day 70 and used to study sperm plasma membrane, substitution and mitochondrial membrane potential. Compared with the control group, the groups receiving L-Cit showed an increase in sperm concentration and number of linear motile sperm (p < .01); a decrease in the number of dead sperm (p < .01); an increase in sperm viability, particularly in groups II and III (p < .01); and an increase in sperm mitochondrial membrane potential (p < .01). Moreover, groups I, II and III showed significantly higher levels of serum gonadotropin-releasing hormone (GnRH), glutathione peroxidase (GSH-Px) and nitric oxide (NO) (p < .01). Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels increased in groups I (p < .05), II (p < .05) and III (p < .01), whereas testosterone (T), catalase (CAT) and superoxide dismutase (SOD) levels increased in groups I and II (p < .01). Serum total antioxidant capacity (T-A) increased (p < .05), whereas both hydroxyl radical (·OH) and peroxy radical ( ) levels decreased (p < .01). Compared with the control, all groups had significantly higher SOD and GSH-Px in their seminal plasma (p < .01), and groups I, II (p < .05 for both) and III (p < .01) had higher levels of GnRH and FSH. LH, CAT and NO levels increased in group I (p < .05), II and III (p < .01 for both); malondialdehyde levels decreased in groups I, II (p < .05 for both) and group III (p < .01); and levels decreased in groups I, II and III (p < .01). Under our experimental conditions, GnRH, FSH, LH, T, CAT, SOD, T-A, GSH-P and NO levels in the serum and seminal plasma of rams receiving L-Cit increased, whereas Oestradiol (E ), and ·OH levels in the seminal plasma decreased; this improved the semen quality of rams supplemented with L-Cit. Moreover, supplementation with 12 g/d gave the best results.
为了为 L-瓜氨酸（L-Cit）在畜牧业中的应用提供理论依据，本研究通过给公羊喂食不同剂量的 L-Cit，研究了 L-Cit 对公羊生殖激素水平、抗氧化能力和精液质量的影响。将 32 只公羊随机分为四组，每组 8 只。在所有公羊都经过正常捐精训练后，对照组喂食基础日粮，而实验组 I、II 和 III 则分别补充 4、8 和 12 g/d 的 L-Cit。实验持续 70 天，期间在第 0、15、30、45 和 60 天从颈静脉采集血样，在第 0、20、40 和 60 天采集精液样本。在同组内，用 100µl 的精液进行质量测试，其余精液样本和血样在 600g 下离心 15 分钟，分别用上清液和血清测定生殖激素和抗氧化指标的水平。在第 70 天还收集了公羊的精液样本，用于研究精子质膜、替代和线粒体膜电位。与对照组相比，接受 L-Cit 的组的精子浓度和直线运动精子数增加（p<.01）；死精子数减少（p<.01）；精子活力增加，尤其是在 II 组和 III 组（p<.01）；精子线粒体膜电位增加（p<.01）。此外，I、II 和 III 组的血清促性腺激素释放激素（GnRH）、谷胱甘肽过氧化物酶（GSH-Px）和一氧化氮（NO）水平显著升高（p<.01）。I、II 和 III 组的促黄体生成素（LH）和促卵泡激素（FSH）水平升高（p<.05），而睾酮（T）、过氧化氢酶（CAT）和超氧化物歧化酶（SOD）水平在 I 组和 II 组升高（p<.01）。血清总抗氧化能力（T-A）升高（p<.05），而羟自由基（·OH）和过氧自由基（ ）水平降低（p<.01）。与对照组相比，所有组的精液质膜中 SOD 和 GSH-Px 均显著升高（p<.01），I、II 组（两者均 p<.05）和 III 组（p<.01）的 GnRH 和 FSH 水平也更高。I 组（p<.05）、II 组和 III 组（两者均 p<.01）的 LH、CAT 和 NO 水平升高；I、II 组（两者均 p<.05）和 III 组（p<.01）的丙二醛水平降低；I、II 和 III 组的 水平降低（p<.01）。在我们的实验条件下，接受 L-Cit 的公羊血清和精液质膜中的 GnRH、FSH、LH、T、CAT、SOD、T-A、GSH-P 和 NO 水平升高，而精液质膜中的雌二醇（E ）、 和·OH 水平降低；这改善了补充 L-Cit 的公羊的精液质量。此外，每天补充 12g 效果最佳。
