热应激对奶牛血液流变学指标及血清无机离子浓度和酶活性的影响

Effects of heat stress on hemorheology status and plasma inorganic ion concentration and plasma enzyme levels in dairy cows

将40头健康娟荷奶牛和荷斯坦奶牛分为2组,分别于冬季12月份(牛舍日平均气温10.35℃,温湿度指数为47.24)和次年夏季7月份(牛舍日平均气温31.07℃,温湿度指数为82.61)测定热应激对奶牛血液流变学指标及血清无机离子浓度和酶活性的影响.结果表明:除血沉外,全血比黏度、血浆比黏度、红细胞压积,荷斯坦奶牛、娟荷奶牛夏季都明显升高,与冬季间差异均极显著(P<0.01),但在夏季或冬季2个品种间差异不显著(P>0.05);血清K+浓度,娟荷奶牛冬季与夏季间差异显著(P<0.05),荷斯坦奶牛冬季与夏季间以及2个品种间差异不显著(P>0.05);热应激极显著降低血清Na+、Ca2+浓度(P<0.01),但夏季或冬季2个品种间差异不显著(P>0.05);血清C l-浓度,2个品种间及2个季节间差异均不显著(P>0.05);热应激显著升高谷丙转氨酶、碱性磷酸酶活性(P<0.05),但夏季或冬季2个品种间差异不显著(P>0.05);谷草转氨酶活性,冬季2个品种间差异显著(P<0.05),夏季2个品种间差异不显著(P>0.05).可见,全血比黏度,血浆比黏度,红细胞压积,血清Na+、Ca2+浓度和谷丙转氨酶、碱性磷酸酶活性与奶牛品种无关,与热应激程度关系密切.

The effects of heat stress on changes in hemorheology and plasma inorganic ion concentration and plasma enzyme levels were evaluated in two groups of 40 healthy Holstein and Jersey x Holstein dairy cow. These animals were subjected to a cool environment when the mean temperature-humidity index （THI） was 47.24 and temperature was 10.35℃ in December. This experiment was repeated in July of the following year, when the mean THI was 82.61 and temperature was 31.07 ℃. Heat stress had no effect on erythrocyte sedimentation rate （ESR） in Holstein and Jersey x Holstein cow but whole blood and plasma viscosity and packed cells volume （PCV） were elevated in summer and had significant differences compared with those in winter （P 〈 0.01 ）, while there were no significant differences between Holstein and Jersey x Holstein cow in summer or winter. In addition, the content of plasma potassium of Jersey x Holstein cow was significanfly different between summer and winter （P 〈 0.05 ） , while there were no significant differences between Holstein and Jersey x Holstein cow, and of Holstein cow between summer and winter. Heat stress extremely significantly decreased plasma natrium and calcium content （P 〈 0.01 ）, while there were no significant differences between Holstein and Jersey x Holstein cow in summer or winter. The content of plasma chloride was not significantly different between two breeds and two seasons. The activities of alanine aminotrasferase （ALT） and alkaline phosphatase （ALP） were significantly elevated （ P 〈 0.05 ） with heat stress in Holstein and Jersey x Holstein cow, but there were no significant differences between two breeds in summer or winter. The aspartic protease （AST） activity was significantly different between Holstein and Jersey x Holstein cow in winter （P 〈0.05） but insignificantly in summer. These results indicated that whole blood and plasma viscosity and PCV, plasma natrium, calcium, and ALT and ALP had close relation with heat-stress, those indexes were independent of dairy breed.