饲粮铬对热应激肉仔鸡免疫功能的影响

EFFECT OF DIETARY CHROMIUM ON IMMUNE RESPONSES IN HEAT STERSSED BROILERS

目的 : 研究饲粮铬源和铬水平对热应激肉仔鸡免疫功能的影响。方法 : 按 2× 5因子安排的完全随机设计 ,将处于热应激条件下的 3 78只 4w龄商品代 Arbor Acres(AA)肉公鸡随机分为 9个处理组 ,分别饲喂含铬 0 .60 mg/kg的未添加铬玉米 -豆粕型基础饲粮 (两种铬源共用0添加组作对照 )和向该基础饲粮中添加 0 .4、2 .0、1 0 .0和 2 0 .0 mg/kg铬分别源于三氯化铬(Cr Cl3)和吡啶羧酸铬的试验饲粮 2 1 d。结果 : 所有观测指标在两种铬源间均无显著差异 ;铬水平对脾重、全血异嗜性白细胞 /淋巴细胞 (H/L)、T淋巴细胞百分率、牛血清白蛋白 (BSA)的血清抗体效价和血浆环磷酸鸟苷 /环磷酸腺苷 (c GMP/c AMP)有显著影响 ,而对胸腺重和法氏囊重无明显影响。随着饲粮铬水平的增加 ,脾重在 2 0 .0 mg/kg铬组达最大 ,H/L比值在 2 0 .0 mg/kg铬组降至最低 ,T淋巴细胞百分率在 2 .0 mg/kg铬组时达到最高 ,血浆 c GMP/c AMP在 1 0 .0 mg/kg铬组时降至最低。在血清 BSA抗体效价上铬源与铬水平间有明显互作效应 ,而在 H/L、T淋巴细胞百分率和血浆 c GMP/c AMP上铬水平与时间有明显互作效应。结论 : 无机三氯化铬与有机吡啶羧酸铬均可提高热应激肉仔鸡的免疫功能 。

Objective: To investigate the effects of dietary Cr source and level on immune responses in heat stressed broilers. Methods: A total of 378 four weeks old Arbor Acres(AA)commercial broilers were allotted to nine treatments in a completely randomized design involving a 2×5 factorial arrangement of treatments, and fed a corn soybean meal basal diet containing 0.60 mg/kg Cr and the basal diets supplemented with 0.4, 2.0, 10.0 or 20.0 mg/kg Cr as either Cr chloride or Cr picolinate under heat stress 〔9∶00 am-17∶00 pm:(36±2) ℃; 19∶00 pm-7∶00 am:(28±2) ℃; and relative humidity: 60%-70%〕 for 21 d. Results: No difference(P>0.10)between the two Cr sources was observed in all indices studied; Cr level affected the relative weight of spleen (P<0.02), blood heterophil/lymphocyte ratio(H/L, P< 0.0001), T lymphocyte percentage (P<0.0001), serum antibody OD value against bovine serum albumin (BSA) (P<0.001), and plasma cGMP/cAMP ratio (P<0.01), but had no effect (P<0.19) on relative weights of thymus and fabricius bursa. As dietary Cr levels increased, the birds fed the diet supplemented with 20.0 mg/kg Cr had the greastest spleen weight and lowest H/L ratio, and those supplemented with 2.0 mg/kg Cr had the highest T lymphocyte percentage, and those supplemented with 10.0 mg/kg Cr had the lowest plasma cGMP/cAMP ratio. Conclusion: The results indicate that both Cr chloride and Cr picolinate can enhance cell mediated and humoral immune responses in heat stressed broilers, and the two Cr sources are effective in alleviating the effect of heat stress.