奶牛血液抗氧化酶活性的季节变化

为了研究奶牛耐热性与体内抗氧化酶活性的相关性,本试验选择胎次相近的35头荷斯坦奶牛,按夏季产奶量下降率分为耐热组(下降率10%以下)和热应激组(下降率40%以上),分别测定春季、夏季试验牛血浆中超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活力,以及丙二醛(malondialdehyde,MDA)含量。结果表明:(1)奶牛血液抗氧化指标受季节性影响较大,夏季血浆中SOD活力、GSH-Px活力极显著低于春季(P<0.01),夏季MDA含量极显著高于春季(P<0.01);(2)血液中抗氧化指标在同一季节、不同组别之间差异较大,春季耐热组SOD活力极显著高于热应激组(P<0.01),耐热组MDA含量显著低于热应激组(P<0.05),夏季耐热组SOD活力、GSH-Px活力显著高于热应激组(P<0.05),耐热组MDA含量显著低于热应激组(P<0.05);(3)夏季奶牛血液中GSH-Px活力及MDA含量分别与夏季奶牛产奶量下降率极显著强负相关(r=?0.710,P<0.01)和极显著强正相关(r=0.733,P<0.01),夏季血液中SOD活力与夏季奶牛产奶量下降率之间没有显著的相关性,夏季GSH-Px活力下降率与产奶量下降率间呈显著正相关(r=0.493,P<0.05),但夏季血液中SOD活力下降率和MDA上升率与夏季奶产量下降率之间无显著的相关性。以上结果提示:(1)奶牛血液抗氧化酶受季节影响较大;(2)奶牛的耐热性可能与血液的抗氧化性相关。

Seasonal Variation of Blood Antioxidant Enzymes in Holstein Cows

In order to study the correlation between thermostability and the activity of antioxidant enzyme of cow,thirty-five Holstein cows were selected and divided into two groups according to descending rate of milk yield in summer compared with the milk yield in spring,descending rate below 10% was in heat-tolerant group,above 40% was in heat-stress group.The activity of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px) and malondialdehyde(MDA) content in plasma were determined both in spring and summer.The results showed(1) antioxidant indices were greatly different between two seasons,the activity of SOD and GSH-Px were lower in summer than that in spring(P<0.01),but MDA content in summer were higher than that in spring(P<0.01);(2) within the same season,the antioxidant indices were different between the two groups,the SOD activity of heat tolerant group in spring were higher than that in heat stress one(P<0.01),MDA content of heat tolerant group were lower than that of heat stress one(P<0.05),but no difference of GSH-Px activity was found between the two groups;in summer,the SOD activity and GSH-Px activity of heat tolerant group were higher than that of heat stress one(P<0.01),but MDA content of heat tolerant group were lower than that of heat stress one.(3)Correlation analysis showed that the plasma GSH-Px activity in summer significantly negatively correlate to the milk yield descending rate(r =-0.710,P<0.01),the variation of GSH-Px activity from spring to summer positively correlate to the milk yield descending rate(r=0.493,P<0.05),the plasma MDA content in summer significantly positive correlate to the milk yield descending rate(r =0.733,P<0.01).However,no correlation was found between the SOD activity in summer,the variation of SOD,MDA from spring to summer and the milk yield descending rate.The results indicated the plasma antioxidant enzymes of dairy cattle were affected by seasonal change greatly,and the blood antioxidizability may correlate to the thermostability of dairy cattle.