慢性冷热应激对放牧西门塔尔牛抗氧化功能及HPA轴、SAM轴激素分泌的影响

为研究慢性冷热应激对放牧条件下西门塔尔牛生理指标、抗氧化功能及下丘脑-垂体-肾上腺皮质轴(HPA)、交感-肾上腺-髓质轴(SAM)激素分泌的影响,选取内蒙古锡林郭勒盟苏尼特左旗某家庭牧场体质量相近、体况健康的西门塔尔牛20头,试验期间测定试验牛生理指标,于试验期最后一天清晨进行颈静脉采血并制备血清,采用ELISA方法检测血清中超氧化物歧化酶(SOD)、丙二醛(MDA)、总抗氧化能力(T-AOC)、谷胱甘肽过氧化物酶(GSH-Px)、促肾上腺皮质激素(ACTH)、糖皮质激素(GC)、肾上腺素(EPI)及去甲肾上腺素(NE)的含量。结果表明,冷热应激对西门塔尔牛产生了一定的应激:冷应激状态下(冬季)西门塔尔牛血清中ACTH、GC含量显著高于热应激状态(夏季)和非应激状态(春季)(P<0.05),夏季和冬季西门塔尔牛血清中NE、EPI含量均显著高于春季(P<0.05);夏季和冬季西门塔尔牛血清中MDA含量显著高于春季(P<0.05),春季和夏季T-AOC含量显著高于冬季(P<0.05),GSH-Px含量在3个季节之间差异不显著(P>0.05)。综上所述,冷热应激降低了西门塔尔牛的抗氧化能力,可能对西门塔尔牛机体造成了一定的损伤;冷热应激激活了西门塔尔牛的HPA轴和SAM轴,进而提高机体对冷热应激的适应能力。

Effects of chronic cold and heat stress on the antioxidant function and hormone secretion of HPA axis and SAM axis of grazing Simmental cattle

In order to study the effects of chronic cold and heat stress on the physiological indexes,antioxidant function and hormones of hypothalamus pituitary adrenocortical axis(HPA)and sympathetic adrenal medullary axis(SAM)of Simmental cattle under grazing conditions,20 Simmental cattle with similar body mass and healthy condition were selected from a family pasture in Sunit Left Banner,Xilingol League,Inner Mongolia.In the morning of the last day of the trial period,blood was collected from jugular vein and serum was prepared.The contents of superoxide dismutase(SOD),malondialdehyde(MDA),total antioxidant capacity(T-AOC),glutathione peroxidase(GSH-Px),adrenocorticotropic hormone(ACTH),glucocorticoid(GC),epinephrine(EPI)and norepinephrine(NE)in serum were detected by ELISA.The results showed that cold and heat stress had some stress on Simmental cattle:ACTH and GC in serum of Simmental cattle under cold stress(winter)were significantly higher than those under heat stress(summer)and no stress(spring)(P<0.05),NE and EPI in serum of Simmental cattle in summer and winter were significantly higher than those in spring(P<0.05),MDA content in serum of Simmental cattle in summer and winter was significantly higher than that in spring(P<0.05),T-AOC content in winter was significantly lower than that in summer and spring(P<0.05),and GSH-Px content in three seasons was no significant(P>0.05).In conclusion,it can be seen that cold and heat stress reduces the antioxidant capacity of Simmental cattle and may cause some damage to the body of Simmental cattle;cold and heat stress activates the HPA axis and SAM axis of Simmental cattle,thus improving the adaptability of the body to cold and heat stress.