不同精粗比日粮对奶山羊瘤胃液pH值、VFA及血液VFA含量的影响

Effects of different dietary concentrate to forage ratios on rumen fluid pH and VFA levels and blood VFA levels in dairy goats

本试验旨在探讨不同精粗比日粮对奶山羊瘤胃液pH值、VFA以及血液中VFA含量的影响。选择8只安装永久性瘤胃瘘管的奶山羊作为试验动物,采用完全随机分组试验设计随机分为2组,分别饲喂精粗比为6∶4和4∶6的日粮,预饲期15 d,采样期3 d。结果表明,高精料组(HC组)瘤胃液pH值显著低于低精料组(HR组)(P<0.05);在采食后3 h,HC组与HR组瘤胃液pH值均下降至最低值,分别为5.71和6.08。除了乙酸含量外,HC组瘤胃液丙酸、异丁酸、丁酸、异戊酸、戊酸以及总挥发性脂肪酸(TVFA)含量分别比HR组提高4.99%、5.58%、21.81%、17.95%、18.27%、1.66%。HC组血浆中各种VFA的含量均高于HR组,其中丙酸、丁酸含量两组间差异达到显著水平(P<0.05)。HC组瘤胃液以及血浆中乙酸与丙酸比值均低于HR组,但两组间差异均不显著(P>0.05)。HC组瘤胃液乙酸、丙酸、TVFA浓度在采食后2 h达到最大值,HR组在采食后3 h达到最大值,两组日粮血浆中VFA浓度均在采食后2 h达到最大值,然后逐渐恢复到采食前水平。结论:高精料日粮导致瘤胃液pH值显著降低,瘤胃液和血浆中VFA含量增加;瘤胃液VFA生成速率HC组高于HR组。

The aim of this study was to evaluate the effect of dietary concentrate to forage ratios on rumen fluid pH and VFA levels and blood VFA levels in dairy goats. Eight dairy goats with permanent tureen fistula were randomly divided into two groups in a randomly block design. Animals were fed two kinds of diets with different concentrate to forage ratios, which were 6 ： 4 （ concentrate ： roughage = 6 ： 4, HC） and 4 ： 6 （concentrate ： roughage：4 ： 6, HR）. The experimental period included 15 days adaptation and 3 days samples collection. The results showed that HC diets decreased pH value of rumen fluids compared with HR diets （ P〈0. 05 ）, the pH value decreased to mini- mum at 3 h post-feeding and the pH value were 5.71 and 6. 08, respectively. Except acetic acid, the concentration of propionate, isobu- tyrate, butyrate, isovalerate, valerate and TVFA of rumen fluids in HC were higher than those in HR and increased 4. 99%, 5.58%, 21.81%, 17.95%, 18. 27%, and 1.66%, respectively. All of plasma VFAs levels in HC group were higher than that in HR group, espe- cially, the concentration of propionate and butyrate reached significant levels （P〈0. 05 ）. The ratio of acetate to propionate of rumen fluid and plasma in goats fed HC diets were both low compared with HR diets, but the difference was not significant （P〉0. 05）. The maximum concentrations of acetate, propionate and TVFA in HC and HR diet were showed at 2 h and 3 h post-feeding, respectively. The maximum plasma concentration of VFA were observed at 2 h post-feeding, and then reduced to before feeding levels gradually in both two diets. It was concluded that the pH value of rumen fluid were decreased significantly and the rumen and plasma concentrations of FA was increased in goats fed HC diets. The production rate of VFA of tureen fluids in goats fed HC diets was high compared with HR diets.