Uyanga Victoria Anthony, Sun Lijing, Liu Yu, Zhang Meiming, Zhao Jingpeng, Wang Xiaojuan, Jiao Hongchao, Onagbesan Okanlawon M, 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 City, Shandong Province, 271018, China.
Department of Animal Physiology, Federal University of Agriculture, Ogun State, Abeokuta P.M.B, 2240, Nigeria.
J Anim Sci Biotechnol. 2023 Feb 1;14(1):9. doi: 10.1186/s40104-022-00817-w.
This study examined the efficacy of L-citrulline supplementation on the arginine/nitric oxide metabolism, and intestinal functions of broilers during arginine deficiency. A total of 288 day-old Arbor Acre broilers were randomly assigned to either an arginine deficient basal diet (NC diet), NC diet + 0.50% L-arginine (PC diet), or NC diet + 0.50% L-citrulline (NCL diet). Production performance was recorded, and at 21 days old, chickens were euthanized for tissue collection.
The dietary treatments did not affect the growth performance of broilers (P > 0.05), although NC diet increased the plasma alanine aminotransferase, urate, and several amino acids, except arginine (P < 0.05). In contrast, NCL diet elevated the arginine and ornithine concentration higher than NC diet, and it increased the plasma citrulline greater than the PC diet (P < 0.05). The nitric oxide concentration in the kidney and liver tissues, along with the plasma and liver eNOS activities were promoted by NCL diet higher than PC diet (P < 0.05). In the liver, the activities of arginase 1, ASS, and ASL, as well as, the gene expression of iNOS and OTC were induced by PC diet greater than NC diet (P < 0.05). In the kidney, the arginase 1, ASS and ASL enzymes were also increased by PC diet significantly higher than the NC and NCL diets. Comparatively, the kidney had higher abundance of nNOS, ASS, ARG2, and OTC genes than the liver tissue (P < 0.05). In addition, NCL diet upregulated (P < 0.05) the mRNA expression of intestinal nutrient transporters (EAAT3 and PEPT1), tight junction proteins (Claudin 1 and Occludin), and intestinal mucosal defense (MUC2 and pIgR). The intestinal morphology revealed that both PC and NCL diets improved (P < 0.05) the ileal VH/CD ratio and the jejunal VH and VH/CD ratio compared to the NC fed broilers.
This study revealed that NCL diet supported arginine metabolism, nitric oxide synthesis, and promoted the intestinal function of broilers. Thus, L-citrulline may serve as a partial arginine replacement in broiler's diet without detrimental impacts on the performance, arginine metabolism and gut health of chickens.
本研究考察了补充L-瓜氨酸对精氨酸缺乏的肉鸡精氨酸/一氧化氮代谢及肠道功能的影响。总共288只1日龄的艾维茵肉鸡被随机分配到精氨酸缺乏的基础日粮组（NC日粮）、NC日粮 + 0.50% L-精氨酸组（PC日粮）或NC日粮 + 0.50% L-瓜氨酸组（NCL日粮）。记录生产性能，21日龄时对鸡实施安乐死以收集组织。
日粮处理对肉鸡的生长性能没有影响（P > 0.05），尽管NC日粮使血浆丙氨酸转氨酶、尿酸和几种氨基酸（精氨酸除外）增加（P < 0.05）。相比之下，NCL日粮使精氨酸和鸟氨酸浓度高于NC日粮，且使血浆瓜氨酸增加幅度大于PC日粮（P < 0.05）。NCL日粮使肾脏和肝脏组织中的一氧化氮浓度以及血浆和肝脏中的eNOS活性升高幅度高于PC日粮（P < 0.05）。在肝脏中，PC日粮诱导的精氨酸酶1、ASS和ASL的活性以及iNOS和OTC的基因表达高于NC日粮（P < 0.05）。在肾脏中，PC日粮使精氨酸酶1、ASS和ASL的酶活性显著高于NC和NCL日粮。相比之下，肾脏中nNOS、ASS、ARG2和OTC基因的丰度高于肝脏组织（P < 0.05）。此外，NCL日粮上调了（P < 0.05）肠道营养转运蛋白（EAAT3和PEPT1）、紧密连接蛋白（Claudin 1和Occludin）以及肠道黏膜防御（MUC2和pIgR）的mRNA表达。肠道形态显示，与NC日粮喂养的肉鸡相比，PC和NCL日粮均改善了（P < 0.05）回肠VH/CD比值以及空肠VH和VH/CD比值。
本研究表明，NCL日粮支持肉鸡的精氨酸代谢、一氧化氮合成，并促进肠道功能。因此，L-瓜氨酸可作为肉鸡日粮中部分精氨酸的替代品，且对鸡的生产性能、精氨酸代谢和肠道健康无不利影响。
