Du Xue, Tong Xiaopeng, Qian Xintong, Zhang Yuanning, Li Duoxi, Liu Xiaojun, Zheng Xianzhong, Zhao Ayong
Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang A&F University, Hangzhou, Zhejiang 311300, PR China.
Longyou Agriculture and Rural Bureau, Quzhou, Zhejiang 324499, PR China.
Poult Sci. 2025 Apr 30;104(8):105234. doi: 10.1016/j.psj.2025.105234.
The aim of the study was to investigate the mechanisms of the N-acetyl-L-glutamic (NAG) diet in improving rooster semen quality after cryopreservation. A total of 60 individually housed chickens were randomly allocated to three groups: a basal diet group (C), a basal diet supplemented with 2 g/kg NAG group (NL), and a basal diet supplemented with 4 g/kg NAG group (NH). Semen quality was evaluated on days 15 and 30, including fresh sperm motility and cryopreservation efficacy. Serum biochemical parameters, hormone levels, immune indices, semen metabolites, and gut microbiota composition were assessed at 30 d. NAG supplementation significantly improved semen quality. At 15 and 30 d, both NL and NH groups showed a significant increase in the total motile sperm ratio (TM) in fresh semen compared to the control (P ≤ 0.05). At 30 d, group NH exhibited significantly higher percentage of sperm in a straight-line trajectory (LIN) in fresh semen than both the C and NL groups. After cryopreservation, the sperm TM and LIN from chickens with NAG dietary for 30 days were significantly better in the NL group compared to C and NH groups (P ≤ 0.05). Metabolomic analysis identified significant upregulation of metabolites, including melatonin and ferulic acid, in cryopreserved semen from NAG-supplemented groups, while 5-hydroxylysine and inosine-1-phosphate were significantly reduced. Serum antioxidant capacity, as measured by glutathione peroxidase (GSH-Px) was significantly higher, while malondialdehyde (MDA) levels lower in NAG groups compared to C (P ≤ 0.05). No significant differences in immune markers or reproductive hormones were observed across groups. Gut microbiota analysis revealed that NAG supplementation enhanced beneficial bacterial populations. In conclusion, NAG supplementation improved sperm motility and cryopreservation outcomes, potentially by increasing the levels of semen melatonin and ferulic acid and reducing the body oxidative stress. And it can improve the overall health level by regulating the gut microbiota through diet. These findings highlight NAG's potential as a dietary supplement to improve semen quality and overall reproductive efficiency in poultry.
本研究的目的是探究N-乙酰-L-谷氨酸（NAG）日粮改善公鸡精液冷冻保存后质量的机制。总共60只单独饲养的鸡被随机分为三组：基础日粮组（C）、添加2 g/kg NAG的基础日粮组（NL）和添加4 g/kg NAG的基础日粮组（NH）。在第15天和第30天评估精液质量，包括新鲜精子活力和冷冻保存效果。在第30天评估血清生化参数、激素水平、免疫指标、精液代谢物和肠道微生物群组成。补充NAG显著改善了精液质量。在第15天和第30天，NL组和NH组新鲜精液中的总活动精子比例（TM）与对照组相比均显著增加（P≤0.05）。在第30天，NH组新鲜精液中直线轨迹精子的百分比（LIN）显著高于C组和NL组。冷冻保存后，NL组中采食NAG日粮30天的鸡的精子TM和LIN显著优于C组和NH组（P≤0.05）。代谢组学分析发现，补充NAG组的冷冻保存精液中包括褪黑素和阿魏酸在内的代谢物显著上调，而5-羟赖氨酸和肌苷-1-磷酸显著减少。与C组相比，NAG组通过谷胱甘肽过氧化物酶（GSH-Px）测量的血清抗氧化能力显著更高，而丙二醛（MDA）水平更低（P≤0.05）。各组之间在免疫标志物或生殖激素方面未观察到显著差异。肠道微生物群分析表明，补充NAG可增加有益细菌种群。总之，补充NAG可改善精子活力和冷冻保存结果，可能是通过提高精液褪黑素和阿魏酸水平以及降低机体氧化应激。并且它可以通过饮食调节肠道微生物群来提高整体健康水平。这些发现突出了NAG作为一种膳食补充剂改善家禽精液质量和整体繁殖效率的潜力。
