地塞米松和饲粮能量水平对肉仔鸡能量采食及神经肽Y基因表达的影响

Effects of Dexamethasone and Dietary Energy Level on Energy Intake and Neuropeptide Y Gene Expression of Broiler Chickens

本试验旨在探讨注射地塞米松(DEX)模拟应激状态下,应激和饲粮能量水平对肉仔鸡能量采食的影响。选取体重相近的180只23日龄的雄性爱拔益加(AA)肉鸡随机分成6组,每组3个重复,每个重复10只鸡。试验采用2×3析因设计,因素为DEX[处理(注射DEX2 mg/kg)、未处理(注射等剂量生理盐水)]和饲粮能量水平[高能(HE)、低能(LE)以及高能、低能自由采食(H-LE)]。预试期5 d,正试期7 d。结果表明:1)DEX处理极显著降低了肉仔鸡的采食量和体增重(P<0.01),极显著提高了耗料增重比、耗能增重比、腹脂率以及血浆葡萄糖、甘油三酯和尿酸的浓度(P<0.01),显著提高了肠道指数(P<0.05)。2)采用LE饲粮体增重(P<0.05)、腹脂率(P<0.01)显著低于其他2种饲粮,耗料增重比显著低于HE饲粮(P<0.05);采用HE饲粮耗能增重比极显著高于其他2种饲粮(P<0.01);采用H-LE饲粮神经肽Y(NPY)基因表达量显著高于LE饲粮(P<0.05)。3)DEX、饲粮能量水平对耗料增重比(P<0.05)和耗能增重比(P<0.01)的影响存在显著的互作效应。结果提示,DEX应激可使肉仔鸡血浆中葡萄糖、尿酸和甘油三酯的浓度升高;DEX应激和HE饲粮均能增加脂肪在腹部沉积,提高耗料增重比和耗能增重比;H-LE饲粮能上调肉仔鸡下丘脑NPY基因表达。

This experiment was conducted to investigate effects of dexamethasone(DEX) and dietary energy level on the energy intake of broiler chickens under the simulative stress induced by DEX injection.One hundred and eighty 23-day-old male broiler chickens(Arbor Acres) were selected and randomly divided into 6 groups with 3 replicates in each group and 10 chickens per replicate.A 2×3 factorial design was used.The factors were DEX [treated(injected with 2 mg/kg DEX) and untreated(injected with physiological saline at an equal dose)] and dietary energy level [high energy(HE),low energy(LE) and freely choose between HE and LE(H-LE)].The pre-experiment lasted for 5 d,and the experiment lasted for 7 d.The results showed as follows: 1) DEX treatment significantly decreased feed intake(P<0.01) and body weight gain(P<0.01),but significantly increased feed/gain(P<0.01),energy/gain(P<0.01),abdominal fat percentage(P<0.01),plasma concentrations of glucose,triglyceride and urate(P<0.01),as well as intestinal tract index(P<0.05).2) Broiler chickens fed LE diet had significantly lower body weight(P<0.05) and abdominal fat percentage(P<0.01) than those fed the other two kinds of diets,and had significantly lower feed/gain than those fed HE diet(P<0.01);broiler chickens fed HE diet had significantly higher energy/gain than those fed the other two kinds of diets(P<0.01);broiler chickens fed H-LE diet had significantly higher gene expression level of NPY than those fed LE diet(P<0.05).3) DEX and dietary energy level had significant interaction effects on feed/gain(P<0.05) and energy/gain(P<0.01).The results indicate that DEX-stress can increase plasma concentrations of glucose,triglyceride and urate;both DEX-stress and HE diet can increase deposition of abdominal fat,feed/gain and energy/gain;H-LE diet can increase NPY gene expression in the hypothalamus of broiler chickens.