体外法研究延胡索酸对瘤胃甲烷、氢气产量和挥发性脂肪酸组成的影响

Effects of Fumarate on Ruminal Methane,Hydrogen Gas Production and Volatile Fatty Acid Composition Using an in Vitro Method

本试验旨在研究不同添加水平的延胡索酸对体外发酵甲烷、氢气产量、挥发性脂肪酸组成以及微生物数量的影响。选用3只装有永久性瘤胃瘘管的成年湘东黑山羊作为瘤胃液供体。试验采用2×4双因子试验设计,以发酵底物和延胡索酸作为影响因素,其中发酵底物分别是菊苣和玉米粉,延胡索酸设定0、3、6和12 mmol/L 4个添加水平,另外设空白组,即发酵瓶中不添加发酵底物,仅添加0、3、6和12 mmol/L延胡索酸用来矫正数据,每组2个平行,重复测定3次。采用全自动体外模拟瘤胃发酵设备,进行72 h体外模拟瘤胃发酵试验。结果表明:1)玉米粉的72 h产气量、干物质消失率均显著高于菊苣(P<0.05)。延胡索酸显著增加了72 h产气量(P<0.05),但对72 h矫正产气量(去除各个添加水平延胡索酸自身的产气量)、干物质消失率无显著影响(P>0.05)。发酵底物和延胡索酸对72 h产气量和干物质消化率不存在显著交互作用(P>0.05)。2)玉米粉的氢气产量和矫正氢气产量只有在12 h显著高于菊苣(P<0.05),而2种底物在其他时间点的氢气产量和矫正氢气产量无显著差异(P>0.05);玉米粉不同时间点甲烷产量和矫正甲烷产量均显著高于菊苣(P<0.05)。延胡索酸对不同时间点甲烷产量、矫正甲烷产量和氢气产量、氢气矫正产量均无显著影响(P>0.05)。延胡索酸和底物对不同时间点的氢气和甲烷产量不存在显著交互作用(P>0.05)。3)延胡索酸显著增加了乙酸、丙酸和总挥发性脂肪酸浓度(P<0.05),显著降低了乙丙比和pH(P<0.05)。但是,延胡索酸对矫正总挥发性脂肪酸浓度没有显著影响(P>0.05)。4)延胡索酸对微生物数量均没有显著影响(P>0.05)。结果提示,和菊苣相比,玉米粉富含更多易发酵碳水化合物,这有助于产生更多的气体和挥发性脂肪酸。延胡索酸可以增加体外产气量和挥发性脂肪酸浓度主要因为延胡索酸在发酵过程中自身可以代谢产生额外的气体和挥发性脂肪酸,这会使产气量和挥发性脂肪酸浓度增加,而对于发酵底物自身的降解和微生物数量没有显著影响。

This study was conducted to investigate the effects of different supplemental levels of fumarate on methane and hydrogen gas production,volatile fatty acids composition and microbial population through in vitro fermentation. Rumen fluid was collected from three adult Xiangdong black goats fitted with permanent rumen cannulation. Using a 2 × 4 two-factor experimental design,corn flour and chicory were selected as substrates,fumarate had four (0,3,6 and 12 mmol/L) final concentrations,and blank groups were set for correcting the results,which were contained no substrate,just contained fumarate at concentrations of 0,3,6 or12 mmol/L,respectively. Each group had 2 replicates,and were replicated 3 times. The 72 h in vitro ruminal incubation was performed using automatic fermentation incubation system. The results showed as follows: 1)the 72 h gas production and dry matter degradation of corn flour were significantly higher than those of chicory (P<0.05). Fumarate supplementation had greater 72 h gas production (P<0.05);however,fumarate supplementation did not alter corrected 72 h gas production and dry matter degradation (P>0.05). There is no interaction between substrates and fumarate on 72 h gas production and dry matter degradation (P>0.05). 2) Hydrogen production and corrected hydrogen production of corn flour at 12 h were significantly higher than those of chicory (P<0.05),those at other time points did not have significant differences (P>0.05);methane production and corrected methane production of corn flour at each time points were significantly higher than those of chicory (P<0.05). Fumarate had no significant effect on methane production,corrected methane production,hydrogen production and corrected hydrogen production at each time points (P>0.05). There is no interaction between substrates and fumarate on hydrogen production and methane production (P>0.05). 3) Fumarate supplementation significantly increaed acetate,propionate and total volatile fatty acids concentrations (P <0.05),and significantly decreased pH and acetate to propionate ratio (P<0.05). But fumarate supplementation had no significant effect on corrected total volatile fatty acids concentrations (P > 0. 05). 4) Fumarate supplementation did not significantly affect microbial population (P>0.05). This study indicates that corn flour contains more fermentable carbohydrates than chicory,which help produce more gas and volatile fatty acids. Fumarate supplementation causes an increase in gas production and total volatile fatty acids concentration,which is mainly due to produce more gas and total volatile fatty acids during fumarate fermentation process,but has no significant effect on substrate self-degradation and microbial population.