日循环高温对肉鸡组织锌离子浓度及金属硫蛋白含量的影响

Effect of Cyclic High Temperatures on the Zn^(2+) Concentration and Metallothionein Content in Tissues of Broilers

本文旨在研究日循环高温对肉鸡肝脏、胰腺及十二指肠锌离子浓度和金属硫蛋白含量的影响。选择32日龄爱拔益加(AA)肉用公鸡120只,随机分为3组(适温组、配对组和高温组),每组4个重复,每个重复10只鸡。适温组及配对组维持恒温23℃,配对组按前1天高温组的采食量饲喂;高温组温度为23℃—33℃—23℃循环变化,自由饮水。结果显示,高温4和8 d可显著降低肉鸡血浆、肝脏、胰腺和十二指肠锌离子浓度(P<0.05),显著升高胰腺金属硫蛋白基因mRNA表达量(P<0.05);高温4 d可显著降低肉鸡肝脏和十二指肠金属硫蛋白含量及其基因mRNA表达量(P<0.05),高温8 d均恢复至正常水平,但显著降低了肉鸡胰腺金属硫蛋白含量(P<0.05);适温组与配对组锌离子浓度、金属硫蛋白含量及金属硫蛋白基因mRNA表达量差异不显著(P>0.05)。本试验结果表明,日循环高温可导致肉鸡肝脏、胰腺及十二指肠锌离子浓度和金属硫蛋白含量下降,其下降与高温导致的肉鸡采食量下降无关,且肉鸡肝脏、胰腺及十二指肠中金属硫蛋白含量与锌离子浓度变化趋势相似。

The experiment was conducted to investigate the effect of cyclic high temperatures on the Zn2＋ concentration and metallothionein content in pancreas,liver and duodenum of broiler chickens.One hundred and twenty 32-day-old Arbor Acres male broilers were randomly allotted to 3 groups（normal-temperature group,paired-feeding group and high-temperature group） with 4 replicates in each group and 10 birds in each replicate.The broilers in the normal-temperature group and paired-feeding group were maintained in a controlled environment temperature at 23 ℃,and the paired-feeding group were matched the diet intake of broilers in high-temperature group at the previous day of the experiment.The broilers in the high-temperature group were housed in a controlled environment temperature with daily cyclic high temperature（23 ℃-33 ℃-23 ℃）,and drinked ad libitum.The results showed as follows： after 4 and 8 d cyclic high temperatures,the Zn2＋ concentration in plasma,liver,pancreas and duodenum of broilers was significantly decreased（P0.05）,and the mRNA expression level of metallothionein gene in pancreas was significantly increased（P0.05）.After 4 d cyclic high temperatures,the metallothionein content and its mRNA expression level in liver and duodenum of broilers were significantly decreased（P0.05）,after 8 d cyclic high temperatures,they became the normol levels,but the metallothionein content in pancreas was significantly decreased（P0.05）;there was no significant differences in the Zn2＋ concentration and metallothionein content,and the mRNA expression level of metallothionein gene between the normal-temperature group and paired-feeding group（P0.05）.In conclusion,cyclic high temperatures significantly decreases the Zn2＋ concentration and metallothionein content in liver,pancreas and duodenum of broilers,which is independent of the decreasing of food intake induced by cyclic high temperatures,and the changing trend of metallothionein content is similar with that of zinc concentration in liver,pancreas and duodenum of broilers.