热应激对西门塔尔种公牛血液生理生化指标和生产性能的影响

Effects of Heat Stress on the Blood Physiological and Biochemical Indexes and Production Performance of Simmental Bulls

为研究热应激对西门塔尔种公牛生理、血清生化指标和精液品质的影响,本研究分别在非热应激(THI=66.67±0.91)和热应激(THI=80.10±1.13)期间连续测定34头体重相近且正常采精的西门塔尔种公牛的生理常值、血清生理生化指标和精液品质指标,并对各项指标进行相关性分析。结果表明:(1)热应激显著提高了西门塔尔种公牛的呼吸频率(RR)、直肠温度(RT)、血清中皮质醇(CoR)和热休克蛋白70(HSP70)水平(P<0.05),显著降低了血清中三碘甲状腺原氨酸(T_(3))和甲状腺素(T_(4))的含量、精子密度和精子活力(P<0.05)。(2)RR、RT、CoR、HSP70与THI呈极显著正相关(P<0.05),T_(3)、T_(4)与THI呈极显著负相关(P<0.05),THI、RR、RT、CoR、HSP70与精子活力呈极显著负相关(P<0.05),T_(3)、T_(4)与精子活力呈极显著正相关(P<0.05)。综上,在夏季高温引起的热应激条件下,西门塔尔种公牛的RR和RT升高,血清中T 3和T 4含量降低,CoR含量和HSP70含量增加可能是引起精液品质下降的原因。因此,生理常值RR和RT,血清生化指标T_(3)、T_(4)、CoR和HSP70可以作为评估西门塔尔种公牛遭受热应激的参考指标。

In order to study the effects of heat stress on the physiology,serum biochemical indexes and semen quality of Simmental bulls,this study continuously measured physiological values,serum physiological and biochemical indexes and semen quality of 34 Simmental bulls with similar body weight and normal semen collection during nonheat stress(THI=66.67±0.91)and heat stress(THI=80.10±1.13).The correlation analysis of each index was carried out.The results showed that:(1)heat stress significantly increased the respiratory rate(RR),rectal temperature(RT),serum cortisol(CoR)and heat shock protein 70(HSP70)levels of Simmental bulls(P<0.05),significantly reduced serum triiodothyronine(T_(3))and thyroxine(T_(4))content,sperm concentration and sperm motility(P<0.05).(2)RR,RT,CoR,HSP70 and THI were significantly positively correlated(P<0.05),T_(3),T_(4)and THI were significantly negatively correlated(P<0.05),THI,RR,RT,CoR,HSP70 were negatively correlated with sperm motility(P<0.05),T_(3),T_(4)are significantly positively correlated with sperm motility(P<0.05).In conclusion,under the heat stress condition caused by high temperature in summer,the content of RR,RT,CoR and HSP70 in Simmental bulls increased,and the content of T_(3)and T_(4)in serum decreased,which may be the reasons for the decline of semen quality.Therefore,the normal physiological values of RR and RT,serum biochemical indicators T_(3),T_(4),CoR and HSP70 can be used as reference indicators for evaluating Simmental bulls suffering from heat stress.