相对湿度和氨气应激对肉仔鸡血氨水平及细胞因子含量的影响

Effects of Relative Humidity and Ammonia Stress on Plasma Ammonia Level and Cytokine Contents of Broilers

本试验旨在研究禽舍环境不同相对湿度(RH)和氨气(NH3)应激对肉仔鸡血氨水平及细胞因子含量的影响。选择288只21日龄体重接近的肉仔鸡,随机分为6个处理,每个处理6个重复,每个重复8只鸡。处理1:30 mg/kg NH3+35%RH;处理2:30 mg/kg NH3+60%RH;处理3:30 mg/kg NH3+85%RH;处理4:70 mg/kg NH3+35%RH;处理5:70 mg/kg NH3+60%RH;处理6:70 mg/kg NH3+85%RH。试验在智能人工气候舱完成,试验期3周。结果表明:1)NH3浓度对血氨水平影响显著(P<0.05),血氨水平随入舱时间的延长而上升。2)RH对入舱3周血清白细胞介素1β(IL-1β)含量影响显著(P<0.05),随入舱时间的延长,血清IL-1β和白细胞介素6(IL-6)含量呈上升的趋势。3)NH3浓度对入舱1、2周血清白细胞介素4(IL-4)含量影响显著(P<0.05),对入舱1、3周血清白细胞介素10(IL-10)含量影响显著(P<0.05)。RH对入舱1周血清IL-10含量影响显著(P<0.05)。由此可见,RH和NH3应激损害了肉仔鸡免疫机能,随着入舱时间的延长,机体获得一定的适应不良环境的能力,对机体的免疫抑制效应具有降低趋势,但70 mg/kg NH3+85%RH对肉仔鸡的免疫抑制不可缓解。

This experiment was conducted to study the effects of high temperature and dietary crude protein level on performance,nitrogen metabolism and emission in broilers aged 28 to 42 days.A total of 576 Arbor Acres broilers were chosen in this experiment and an experimental design with 2 factors and 3 levels per factor was used：factor 1 was feeding mode,namely,23 ℃ ad libtum （AL）,23 ℃ pair-fed （PF,the diet was supplied according to the feed intake of broilers at a cyclic high temperature of 28 ℃-32 ℃-28 ℃） and 28/32 ℃ ad libtum （AL,at a cyclic high temperature of 28 ℃-32 ℃-28 ℃） ; factor 2 was dietary crude protein level,namely,21.19%,18.18% and 14.90%,and Met,Lys,Thr and Trp levels in the diets of all groups were the same and could meet the need of broilers by supplementing synthetic essential amino acids.The broilers were randomly divided to 9 groups with 8 replicates per group and 8 broilers per replicate.The results showed as follows：1） at the same dietary crude protein level,the body weight （BW）,average daily gain （ADG） and average daily feed intake （ADFI） of 28/32 ℃ AL group were significantly lower than those of 23 ℃ AL group （P 〈 0.01）,but were not significantly different from those of 23 ℃ PF group （P 〉 0.05）.Compared with 23 ℃ AL group,the nitrogen utilization of 28/32 ℃ AL group was significantly decreased （P 〈0.01）,while nitrogen excretion per feed intake was significantly increased （P 〈 0.05）.2） When dietary crude protein level was reduced from 21.19% to 14.90% and synthetic essential amino acids were supplemented,nitrogen excretion per weight gain and nitrogen excretion per feed intake were significantly decreased （P 〈0.01）,but nitrogen utilization,BW,ADG and ADFI were not significantly changed （P 〉 0.05）.In conclusion,under the daily cycle high temperature condition,performance and nitrogen utilization are significantly decreased,and nitrogen emission is significantly increased.By adding supplemental synthetic essential amino acids,as dietary crude protein level is reduced to 14.90%,nitrogen emission decreases without affecting BW,ADG and ADFI of broilers. Keywords：high temperature; crude protein; broiler; performance; nitrogen emission