中文摘要：

本试验旨在研究L-亮氨酸（Leu）对猪流行性腹泻病毒（PEDV）感染幼龄仔猪血液指标和空肠免疫相关基因m RNA表达量的影响,探索Leu对PEDV感染仔猪应激的缓解作用。选用30头体重相近的7日龄PEDV阴性仔猪,随机分为3个处理组：对照组、PEDV组和PEDV＋Leu组,每个处理10个重复,每个重复一头猪。试验期10 d（7日龄~16日龄）。从第0天开始对PEDV＋Leu组按2.8 g/kg体重饲喂Leu,而对照组和PEDV组均按4.1 g/kg体重饲喂L-丙氨酸。第7天早上对PEDV组和PEDV＋Leu组采用口服的方式接种106.5TCID50的PEDV,同时对照组采用口服的方式接种等剂量的生理盐水,3 d后（16日龄）取血液和肠道样品。结果表明：与对照组相比,PEDV组仔猪血液中总胆红素（TBIL）水平、血小板分布宽度（PDW）及空肠黏膜CXCL11、REG3G m RNA表达量分别降低了20.92%、9.76%、56.00%、36.00%（P〈0.05）,血液中白细胞（WBC）和淋巴细胞（LYM）数量、磷酸丝氨酸、酪氨酸和色氨酸浓度,及空肠粘膜GSTO2和HSPH1 m RNA水平分别提高了61.68%、27.66%、30.39%、50.54%、64.00%、75.00%、89.00%（P〈0.05）;与PEDV组相比,PEDV＋Leu组仔猪血液中组氨酸、天冬酰胺、尿素氮（BUN）浓度分别升高了55.43%、32.58%、83.33%（P〈0.05）,而二胺氧化酶（DAO）含量、单核细胞（MONO）、单核细胞比（Monocyte Ratio,MONOR）、磷酸丝氨酸、谷氨酸、异亮氨酸、精氨酸、苏氨酸及空肠黏膜MX1和GSTO2 m RNA水平分别降低了28.80%、47.13%、43.87%、10.53%、42.12%、29.48%、29.82%、33.50%、32.11%、28.00%（P〈0.05）。因此,日粮中添加Leu提高了PEDV感染仔猪的免疫功能,缓解了PEDV感染仔猪的应激。

英文摘要：

This experiment was conducted to study the effects of leucine （Leu）on blood biochemical parameters and immune-related genes in the jejunum mucosa of piglets infected by PEDV,thereby to determine whether Leu can relieve the stress on piglets caused by PEDV.A total of 30 7-day piglets of similar weight without PEDV were selected and randomly di-vided into three treatment groups：control group,PEDV group, PEDV＋Leu group.Each group had 10 replicates with 1 piglet each.The experiment lasted for 10 days.Piglets in PEDV ＋ Leu group were fed with Leu at the dosage of 2.8 g per kilogram of body weight per day,whereas those in control and PEDV groups were fed with L-alanine at the dosage of 4.1 g per kilogram of body weight per day.On the morning of the 7th day,piglets in PEDV and PEDV＋Leu group were vaccinated orally with 1065 TCID50 PEDV,while those in the control group treated with same dose of saline solution.The results showed that： com- pared with control group,the number of white blood cells （WBC）and lymphocytes （LYM）,the concentration of phosphoser- ine, tyrosine,tryptophan in blood,and the expressions of GSTO2 and HSPH1 gene in jejunum mucosa were significantly im-proved by 61.68%, 27.66%, 30.39%, 50.54%, 64.00%, 75.00%, 89.00% respectively （P 〈 0.05） , but the TBIL,PDW in the blood,and the expressions of GSTO2 and HSPH1 gene in jejunum mucosa in PEDV group were decreased by 20.92%, 9.76%, 56.00%, 36.00%（P 〈 0.05）.Compared with PEDV group, the expressions of GSTO2 and MX1 gene in jejunum,mononuclear cell （MONO）, MONOR, phosphoserine, glutamic acid, isoleucine, arginine, threonine,and DAO in blood were significantly decreased by 28.00% , 32.11% , 47.13% , 43.87%, 10.53%, 42.12%, 29.48%, 29.82%, 33.50%, 28.80% （P 〈 0.05）,while histidine, urea,and asparagine were sig-nificantly increased by 55.43%, 83.33%, 32.58%（P 〈 0.05）.In conclusion,Leu may improve the immune function of piglets and partially mitigate the st