Reducing crude protein and supplementation with synthetic amino acids in poultry nutrition is a recent trend to avoid wastage of protein and ammonia in production systems. Stress has been shown to impair intestinal barrier and increase inflammatory response. This study was performed on intestinal tissues of broiler chickens to understand the mechanism of stress induced by a synthetic glucocorticoid, dexamethasone (DEX) and the effect of supplementation of arginine, glutamine and glycine in reduced protein diets. Intestinal tissue samples from a previous study were utilized. Male Ross 308 chickens received a basal diet for the first seven days and then fed with crude protein that was reduced to 194 g/kg in grower experimental diets supplemented with glutamine, glycine and additional arginine at 10, 10 and 5 g/kg respectively. Half of the 96 individual birds were injected with DEX (0.5 mg/kg body weight) or saline on days 14, 16, 18 and 20 of age. mRNA expression for jejunum and ileum for amino acid transporters (y+LAT‐1, B^o,+AT, EAAT‐3 and CAT‐1), mechanistic genes (SGLT‐1, mTOR, IAP and FABP‐2) and pro‐inflammatory genes (MUC‐2, NF‐κB, iNOS, IL‐8 and IL‐1β) were analysed using real‐time PCR. The results showed that DEX decreased y+ LAT1 in jejunum, B^o,+AT and EAAT‐3 in ileum. Arginine increased CAT‐1 in the jejunum and ileum under DEX treatment. Through an interaction, DEX reduced IAP in jejunum of glycine and arginine supplemented group and reduced mTOR in jejunum independently. DEX reduced MUC‐2 and iNOS in jejunum and increased iNOS and IL8 in the ileum. Amino acid supplementation did not appear to ameliorate these effects; however, there were some positive effects of glycine on NF‐κB and arginine through increased CAT‐1. Mechanistic understanding of amino acid supplementation in broiler diets warrants further research particularly when dietary protein is reduced below the level tested in the present study.

中文翻译：

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在地塞米松刺激下，饲喂补充精氨酸、谷氨酰胺和甘氨酸的低蛋白日粮的肉鸡空肠和回肠中编码机制途径、营养和氨基酸转运蛋白的选定基因的表达。

在家禽营养中减少粗蛋白和添加合成氨基酸是避免生产系统中蛋白质和氨浪费的最新趋势。压力已被证明会损害肠道屏障并增加炎症反应。本研究对肉鸡的肠道组织进行了研究，以了解合成糖皮质激素地塞米松 (DEX) 诱导应激的机制以及在低蛋白日粮中补充精氨酸、谷氨酰胺和甘氨酸的效果。使用来自先前研究的肠组织样本。雄性 Ross 308 鸡在前 7 天接受基础日粮，然后饲喂粗蛋白，在添加谷氨酰胺、甘氨酸和额外的精氨酸分别为 10、10 和 5 g/kg 的生长试验日粮中，粗蛋白降低至 194 g/kg。96 只鸡中有一半在第 14、16、18 和 20 天时注射了 DEX（0.5 毫克/公斤体重）或生理盐水。空肠和回肠氨基酸转运蛋白的 mRNA 表达 (y+LAT-1, B^o,+ AT、EAAT-3 和 CAT-1）、机制基因（SGLT-1、mTOR、IAP 和 FABP-2）和促炎基因（MUC-2、NF-κB、iNOS、IL-8 和 IL ‐1β) 使用实时 PCR 进行分析。结果表明，DEX 降低了空肠中的 y+ LAT1、B ^{o 、+}回肠中的 AT 和 EAAT-3。在 DEX 治疗下，精氨酸增加了空肠和回肠中的 CAT-1。通过相互作用，DEX 降低了甘氨酸和精氨酸补充组的空肠 IAP，并独立降低了空肠中的 mTOR。DEX 减少空肠中的 MUC-2 和 iNOS，增加回肠中的 iNOS 和 IL8。补充氨基酸似乎没有改善这些影响；然而，甘氨酸通过增加 CAT-1 对 NF-κB 和精氨酸有一些积极影响。对肉鸡日粮中氨基酸补充的机制理解值得进一步研究，特别是当日粮蛋白质减少到本研究中测试的水平以下时。