体外法研究L-苹果酸对瘤胃发酵参数的影响

Effects of L-malic acid on rumen fermentation parameters in vitro

为了研究L-苹果酸不同添加量对体外瘤胃发酵参数的影响,试验采用体外发酵法,选择4个不同的L-苹果酸添加量(A组不添加、B组5 mmol/L、C组10 mmol/L、D组15 mmol/L)进行8,16,24,48 h的体外发酵,对干物质消失率、pH值、氨态氮、微生物蛋白和挥发性脂肪酸浓度进行测定。结果表明:在各发酵时间下,产气量随着L-苹果酸添加量的增加而增加,B、C、D组的干物质消失率(除B组发酵16 h的干物质消失率外)显著高于A组(P<0.05)。发酵48 h,C、D组氨态氮浓度和微生物蛋白浓度均显著高于A、B组(P<0.05),C、D组间差异不显著(P>0.05)。在各发酵时间下,挥发性脂肪酸浓度随着L-苹果酸添加量的增加呈现上升的趋势,其中D组达到最大值,但C、D两组间差异不显著(P>0.05)。说明添加L-苹果酸可以提高底物发酵水平,提高发酵液的氨态氮浓度、微生物蛋白浓度和挥发性脂肪酸浓度,改善瘤胃发酵能力,考虑到成本,10 mmol/L添加量综合效果最佳。

In order to study the effect of different amounts of L-malic acid on rumen fermentation parameters in vitro, the influence of four different amounts of L-malic acid(group A was not added, 5 mmol/L in group B,10 mmol/L in group C,15 mmol/L in group D) were selected for the in vitro fermentation for 8, 16, 24 and 48 h, then the dry matter disappearance rate, pH value, ammonia nitrogen, microbial protein and volatile fatty acid were determined. The results showed that the gas production increased with the increase of the amount of L-malic acid addition at each fermentation time, and the dry matter disappearance rates in groups B, C and D(except for 16 h of fermentation time in group B) were significantly higher than that in group A(P<0.05). After 48 h of fermentation, the concentrations of ammonia nitrogen and microbial protein in group C and D were significantly higher than those in group A and B(P<0.05), and the difference between C and D groups was not significant(P>0.05). At each fermentation time, the concentration of volatile fatty acids increased with the increase of the amount of L-malic acid, the concentration of volatile fatty acids in group D reached the maximum value, and the difference between C and D groups was not significant(P>0.05). The results showed that the addition of L-malic acid could improve the substrate fermentation level, the concentration of ammonia nitrogen, microbial protein and volatile fatty acid in the fermentation broth, and improve the rumen fermentation condition. Considering the cost, the comprehensive effect of adding 10 mmol/L was the best.