不同热应激条件下添加二氢吡啶对奶牛瘤胃发酵功能的影响

Influence of DHP on the Rumen Fermentation of Dairy Cows in Different Heat Stress Levels

[目的]研究不同热应激条件下添加二氢吡啶对奶牛瘤胃发酵功能的影响。[方法]试验选取6头三胎次泌乳中期中国荷斯坦奶牛,采用自身前后对照,分为4个时期:无应激且不添加二氢吡啶(NS-ND)、无应激添加二氢吡啶(NS-D)、应激但不添加二氢吡啶(S-ND)、应激且添加二氢吡啶(S-D),二氢吡啶添加量为每头牛3.0g/d(即0.6mg/kg体重)。[结果]S-ND时期与NS-ND时期相比,瘤胃液中pH值降低,NH3-N浓度极显著升高(P<0.01),瘤胃液内挥发性脂肪酸(VFA)的浓度显著下降(P<0.01),其中乙酸的百分比含量下降,丙酸和丁酸的百分比含量升高,但差异不显著(P>0.05),乙丙比呈稍下降趋势,差异不显著(P=0.13);应激和无应激时期添加二氢吡啶后,有使瘤胃液pH降低的趋势,NH3-N浓度均显著降低(P<0.01),VFA的浓度显著提高(P<0.01),乙丙比显著增高(P<0.01)。[结论]添加二氢吡啶对提高热应激时期奶牛瘤胃的发酵功能有良好效果。

[Objective]This paper was conducted to investigate the effect of dihydropyridine （DHP） on rumen fermentation in different heat stress levels. [Method]Six dairy cows in mid lactation were used. There were four periods in this research： unstressed without DHP （NS-ND）, unstressed with DHP （NS- D）, stressed without DHP （S-ND） ,stressed with DHP （S-D）. Cows were fed with DHP for 3.0 g/d per cow. [Result]The result showed that there was a decrease tendency of ruminal pH values with the increase of the environmental THI, NH3-N concentration increased significantly （ P 〈0.01）, concentration of total VFA in the rumen reduced （ P 〈0. 01）, the proportion of acetic acid among other VFA also reduced throughout the stress shifts （P 〉0.05）, while propionic and butyric acids, demonstrated an opposite tendency （ P ）0.05）. Accordingly, the ratio of acetic acid to propionic acid decreased with the stress in creasing （P=0.13）. In NS-D and S-D period （ P d0.05）,ruminal pH values reduced,NH3-N concentra tion reduced （ P d0.01） ,concentration of total VFA in the rumen increased （ P 〈0.01） and the ratio of acetic acid to propionic acid tended to increase due to DHP addition （ P 〈0.01） compared with NS-ND and S-ND period. [ConclusionlDHP can improve rumen fermentation pattern in heat stress period and its effect is beneficial.