延胡索酸二钠对瘤胃微生物体外发酵的影响

Effect of disodium fumarate on in vitro fermentation of mixed rumeinal micro-organisms

采用体外批次培养，研究了不同浓度（0、4、7和10mmol·L^-1）延胡索酸二钠对山羊瘤胃微生物体外发酵高精料（玉米粉、豆粕粉及羊草粉，质量比为5：2：3）的影响，同时探讨了延胡索酸二钠对瘤胃微生物发酵的动态过程的影响。结果表明，与对照组相比，延胡索酸二钠可提高体外培养体系中总挥发性脂肪酸浓度（TVFA），显著提高总挥发性脂肪酸中丙酸的比例（P〈0．05），但乙酸／丙酸值、乳酸及氨氮浓度显著降低（P〈0．05），对各指标的影响程度未呈现出一致的剂量效应。动态研究表明，在整个发酵期间，延胡索酸二钠处理组的累计产气量均高于对照组，在12～24h发酵期间，延胡索酸二钠处理组的pH值极显著高于对照组（P〈0．01）。除8h点外，在其他时间点，延胡索酸二钠处理组的乳酸浓度与对照组间无显著差异（P〉0．05）。在8～24h期间，延胡索酸二钠处理组的TVFA及丙酸比例均显著高于对照组（P〈0．05）。发酵过程中，延胡索酸二钠处理组的羧甲基纤维索酶活性峰值显著高于对照组（P〈0．05），而淀粉酶活性峰值显著低于对照组（P〈0．05）。结果提示，延胡索酸二钠能提高发酵体系中的pH值，降低乳酸浓度，改变瘤胃发酵模式。

The influence of disodium fumarate with final concentrations at 0, 4, 7 and 10 mmol·L^-1 on in vitro fermentation of high concentrate （m （corn powder） ： m （soybean meal） ： m （Chinese ryegrass） = 5： 2： 3） was investigated using mixed rumen micro-organisms of goats as inoculum. Resuhs showed that as compared with the control, total volatile fatty acids （TVFA）, the percentage of propionate and total gas production for the disodium fumarate treatment increased significantly （P 〈 0.05）, while the ratio of acetate to propionate and lactate production decreased significantly. A time course study was also conducted to investigate the effect of disodium fumarate at 7 mmol·L^-1 on the fermentation kinetics of rumen micro-organisms. The results showed that the cumulative gas production was higher than that of the control during the incubation. From 12 h to 24 h of incubation, the pH value for the treatment was higher than that of the control （P 〈 0.01）. No significant difference was observed between the disodium fumarate treatment and the control in lactate production at most sampling time, except for the 8 h samples. As compared with the control, the TVFA and propionate production were higher （P 〈 0.05） from the 8 h to 24 h of incubation. The CMCase activity at 12 h was higher than that of the control （P 〈 0.05）, while the amylase activity at 8 h was lower compared with the control （P 〈 0.05）. The results suggested that the addition of disodium fumarate to ruminant feed could stimulate the in vitro fermentation of rumen microorganisms, while reduce lactic acid production.