谷氨酰胺,体内最丰富的氨基酸之一,已被证明对猪发挥各种有益作用。然而,关于饮食谷氨酰胺在低蛋白饮食仔猪中的作用的知识仍然很少。本研究旨在探讨不同水平L-谷氨酰胺对生长性能的影响,血清生化参数,氧化还原状态,氨基酸,低蛋白饲粮仔猪的粪便微生物群。将128只健康杂交仔猪(长白猪×约克郡)随机分为4组,每组4只,每笔8只小猪。4组仔猪分别饲喂以玉米和豆粕为主的低蛋白日粮(粗蛋白水平,17%)包含0%,1%,2%,和3%的L-谷氨酰胺,分别,持续28天。施用1%L-谷氨酰胺的猪在第28天的体重和平均日增重(ADG,P<0.01),而从d1到28较低的饲料增重比(F:G)(P<0.01),与其他三组相比。此外,在d14和28,ADG,平均日采食量,2%和3%L-谷氨酰胺处理比0%和1%L-谷氨酰胺处理对d15至28和d1至28的F:G更高(P<0.01)。此外,1%L-谷氨酰胺降低血清葡萄糖,丙二醛,过氧化氢浓度和抑制天冬氨酸氨基转移酶,丙氨酸氨基转移酶,第14天低蛋白饲粮仔猪的髓过氧化物酶活性,同时伴随过氧化氢酶的上调,总超氧化物歧化酶活性和谷胱甘肽水平(P<0.05)。然而,饲粮3%L-谷氨酰胺可提高第14天猪血尿素氮含量(P<0.05)。进一步调查显示,1%L-谷氨酰胺上调血清谷氨酰胺,赖氨酸,蛋氨酸,酪氨酸,血浆缬氨酸含量降低(P<0.05)。此外,1%L-谷氨酰胺上调p_75_a5、梭菌、乳酸菌,普雷沃科_普雷沃氏菌,第14天仔猪粪便中的Gemmiger,链球菌水平随之降低(P<0.05)。总的来说,日粮1%L-谷氨酰胺可提高低蛋白日粮仔猪的生长性能,改善血清理化指标和抗氧化能力,通过调节氨基酸水平与谷胱甘肽合成增加有关,以及肠道菌群的优化。
Glutamine, one of the most abundant amino acids in the body, has been shown to exert various beneficial effects in pigs. However, knowledge regarding the role of dietary glutamine in low-protein diet-fed piglets remains scarce. The present study aimed to investigate the effects of different levels of L-glutamine on growth performance, serum biochemistry parameters, redox status, amino acids, and fecal microbiota in low-protein diet-fed piglets. A total of 128 healthy crossbred piglets (Landrace × Yorkshire) were randomly allocated into 4 groups of 4 replicate pens, with 8 piglets per pen. Piglets in the 4 groups were fed with corn and soybean meal-based low-protein diets (crude protein level, 17%) that contained 0%, 1%, 2%, and 3% L-glutamine, respectively, for 28 d. Pigs administered 1% L-glutamine had greater body weight on d 28 and average daily gain (ADG, P < 0.01), whereas a lower feed to gain ratio (F:G) from d 1 to 28 (P < 0.01), compared to the other three groups. Besides, lower body weight on d 14 and 28, ADG, average daily feed intake, and higher F:G from d 15 to 28 and d 1 to 28 were observed in response to 2% and 3% L-glutamine treatments than 0% and 1% L-glutamine treatments (P < 0.01). Moreover, 1% L-glutamine reduced serum glucose, malondialdehyde, hydrogen peroxide concentrations and inhibited aspartate aminotransferase, alanine aminotransferase, myeloperoxidase activities in low-protein diet-fed piglets on d 14, with concomitantly upregulated catalase, total superoxide dismutase activities and glutathione level (P < 0.05). However, dietary 3% L-glutamine enhanced blood urea nitrogen content in pigs on d 14 (P < 0.05). Further investigation revealed that 1% L-glutamine upregulated the serum glutamine, lysine, methionine, tyrosine, and reduced plasma valine content (P < 0.05). Additionally, 1% L-glutamine upregulated the abundance of p_75_a5, Clostridium, Lactobacillus, Prevotellaceae_Prevotella, and Gemmiger in the stool of piglets on d 14, with the Streptococcus level being concomitantly reduced (P < 0.05). Collectively, dietary 1% L-glutamine enhances the growth performance and improves serum physiochemical parameters and antioxidative capacity in low-protein diet-fed piglets at an early age, which are associated with an increased synthesis of glutathione by modulating amino acid levels, and the optimization of gut microbiota.