高精料条件下延胡索酸对山羊瘤胃微生物体外发酵的影响

Effect of fumarate on in vitro of fermentation high concentrate substrate by mixed ruminal micro-organisms of goats

通过山羊瘤胃液的体外批次培养，研究延胡索酸对瘤胃混合细菌体外发酵的影响。瘤胃液在含底物（玉米粉、豆粕和黑麦草）和延胡索酸（0、4、8和12mmol·L^-1）条件下发酵24h。结果表明，在整个发酵期内，不同浓度的延胡索酸均显著提高了累积产气量，同时显著影响总挥发性脂肪酸（TVFA）浓度及其组成，降低乙酸的浓度及比例，增加丙酸的浓度及比例。其中4mmol·L^-1延胡索酸在12—24h提高了TVFA浓度和丙酸浓度（P〈0．05），8mmol·L^-1组和12mmol·L^-1组的TVFA浓度和丙酸浓度在16h和24h也有显著提高（P〈0．05）。在12、16、20和24h时，3个添加组乙酸比例均显著低于对照组（P〈0．05），而丙酸比例则明显提高（P〈0．01），乙酸和丙酸的比值显著降低（P〈0．05）。4mmol·L^-1延胡索酸添加组的乳酸浓度在12、16、20和24h均极显著低于对照组（P〈0．01）。结果提示，延胡索酸能显著提高瘤胃微生物体外发酵液中TVFA及丙酸比例，其中4mmol·L^-1延胡索酸对于调控瘤胃微生物体外发酵效果最佳。

The effect of fumarate on rumen fermentation was investigated by in vitro batch cultures of mixed rumen micro-organisms collected from goats. Substrate containing corn powder, soybean meal and ryegrass was fermentated in the presence of fumarate （0, 4, 8 and 12 mmol ·L^-1 ） for 24 h. The results showed that all fumarate treatments increased the cumulated gas production during the whole fermentation period. Fumarate had significant effects on the concentration and composition of total volatile fatty acid （ TV- FA）, The 4 mmol ·L^-1 fumarate increased TVFA and propionate concentration during 12 - 24 h （ P 〈 0. 05 ）, while 8 mmol·L^-1 and 12 mmol·L^-1 fumarate had its effect at 16 h and 24 h. The proportion of acetate in three treatments decreased significantly in 12 - 24 h （ P 〈 0.05 ）, while the proportion of propionate increased significantly （ P 〈 0. 01 ）, resulting in a significant decrease in the ratio of acetate/propionate （ P 〈 0. 05 ）. The lactate concentration in the 4 mmol·L^-1 fumarate treatment was significantly lower than the control from 12 h to 24 h （ P 〈0.01 ）, while the other two treatments had no apparent effect. The results suggested that fumarate could change rumen fermentation pattern with a significant increase of TVFA and propionate ratio, of which 4 mmol·L^-1 fumarate was the optimal dose to modulate the ruminal micro-organism fermentation.