Uyanga Victoria A, Jiao Hongchao, Zhao Jingpeng, Wang Xiaojuan, Lin Hai
Department of Animal Science, College of Animal Science and Veterinary Medicine, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control, Shandong Agricultural University, No. 61 Daizong Street, Tai'an, 271018 Shandong China.
J Anim Sci Biotechnol. 2020 Oct 12;11:103. doi: 10.1186/s40104-020-00507-5. eCollection 2020.
L-citrulline (L-Cit), a non-protein amino acid, has been implicated in several physiological functions including anti-inflammatory, anti-oxidative, and hypothermic roles, however, there is a paucity of information with regards to its potential in poultry production.
This study was designed to investigate the effects of dietary L-Cit supplementation on the production performance, nitric oxide production, and antioxidant status of laying hens during summer period. Hy-Line Brown laying hens ( = 288, 34 weeks old) were allotted to four treatment, 6 replicates of 12 chickens each. Dietary treatments of control (basal diets), 0.25%, 0.50% and 1.00% L-Cit supplementation were fed to chickens for eight (8) weeks. Production performance, free amino acid profiles, nitric oxide production, and antioxidant properties were measured. Blood samples were collected at the 4 and 8 weeks of the experiment.
Air temperature monitoring indicated an average daily minimum and maximum temperatures of 25.02 °C and 31.01 °C respectively. Dietary supplementation with L-Cit did not influence ( > 0.05) the production performance, and rectal temperature of laying hens. Egg shape index was increased ( < 0.05) with increasing levels of L-Cit. Serum-free content of arginine, citrulline, ornithine, tryptophan, histidine, GABA, and cystathionine were elevated, but taurine declined with L-Cit diets. Plasma nitric oxide (NO) concentration was highest at 1% L-Cit. Likewise, nitric oxide synthase (NOS) activity for total NOS (tNOS) and inducible NOS (iNOS) were upregulated with increasing L-Cit levels, although, tNOS was not affected at the 4 week. Anti-oxidant enzymes including catalase and superoxide dismutase (SOD) were increased with L-Cit supplementation, however, SOD activity was unchanged at 4 week, while total anti-oxidant capacity increased at the 8 week. L-Cit supplementation attenuated the extent of lipid peroxidation, and also inhibited glutathione peroxidase activity.
Dietary L-Cit supplementation modulated systemic arginine metabolism, nitric oxide synthesis, antioxidant defense system, and increased the egg shape index of laying hens during the summer season. 1% L-Cit supplementation proved most effective in potentiating these effects and may be adopted for feed formulation strategies.
L-瓜氨酸（L-Cit）是一种非蛋白质氨基酸，具有多种生理功能，包括抗炎、抗氧化和降温作用，然而，关于其在禽类生产中的潜力的信息却很少。
本研究旨在调查夏季日粮中添加L-瓜氨酸对蛋鸡生产性能、一氧化氮生成和抗氧化状态的影响。将海兰褐蛋鸡（n = 288，34周龄）分为四个处理组，每组6个重复，每个重复12只鸡。对照组（基础日粮）、添加0.25%、0.50%和1.00% L-瓜氨酸的日粮分别饲喂鸡8周。测定生产性能、游离氨基酸谱、一氧化氮生成和抗氧化特性。在实验的第4周和第8周采集血样。
气温监测表明，日平均最低和最高温度分别为25.02℃和31.01℃。日粮中添加L-瓜氨酸对蛋鸡的生产性能和直肠温度没有影响（P>0.05）。随着L-瓜氨酸水平的增加，蛋形指数升高（P<0.05）。日粮中添加L-瓜氨酸后，血清中精氨酸、瓜氨酸、鸟氨酸、色氨酸、组氨酸、γ-氨基丁酸和胱硫醚的游离含量升高，但牛磺酸含量下降。血浆一氧化氮（NO）浓度在L-瓜氨酸添加量为1%时最高。同样，随着L-瓜氨酸水平的增加，总一氧化氮合酶（tNOS）和诱导型一氧化氮合酶（iNOS）的一氧化氮合酶（NOS）活性上调，尽管在第4周时tNOS不受影响。添加L-瓜氨酸可提高过氧化氢酶和超氧化物歧化酶（SOD）等抗氧化酶的活性，然而，第4周时SOD活性未发生变化，而第8周时总抗氧化能力增加。添加L-瓜氨酸可减轻脂质过氧化程度，并抑制谷胱甘肽过氧化物酶活性。
夏季日粮中添加L-瓜氨酸可调节全身精氨酸代谢、一氧化氮合成、抗氧化防御系统，并提高蛋鸡的蛋形指数。添加1% L-瓜氨酸在增强这些作用方面最为有效，可用于饲料配方策略。
