不同剂量黄曲霉毒素B_1对奶牛瘤胃混合微生物发酵的抑制作用

Inhibitory Effect of Different Levels of Aflatoxin B1 Addition on Fermentation Characteristic of Mixed Rumen Microorganisms In vitro

通过体外发酵培养,测定发酵液中pH、总挥发性脂肪酸、氨态氮、气体成分及各种纤维素酶活等指标,探讨黄曲霉毒素B(AFB_1)对瘤胃微生物代谢的影响。试验通过瘤胃微生物在体外静态培养中添1加不同浓度的AFB(0,0.1,1,10μg/mL)后,检测培养体系中微生物的活性变化情况。结果表明AFB_1对1苜蓿发酵的抑制作用强于对玉米发酵的作用。添加AFB1会降低氨态氮浓度(P<0.05);总挥发性脂肪酸的产量也会随AFB1添加量的增加而减少,且在玉米组中总挥发性脂肪酸产量高于苜蓿组32.1%(P<0.05);随着AFB_1添加量的增多,乙酸、丙酸、丁酸和戊酸产量逐渐下降(P<0.05),且高剂量二甲基亚砜的添加可导致苜蓿和玉米发酵生成的异戊酸摩尔比例分别升高30%和20%;同时AFB_1会减少甲烷的产量并且对羧甲基纤维素酶活和微晶纤维素酶活也有抑制作用(P<0.05)。说明随着黄曲霉毒素量的增大,瘤胃液中微生物的活性会受抑制,尤其是纤维性饲料的发酵。

The objective of this study was to estimate the effect of the aflatoxin B1 on the metabolism of rumen microorganisms by some fermented parameters such as pH, volatile fatty acid, NH 3 -N, the composition of gas, and the activity of several celluloses. The experiment was to determination the active change of rumen flora in the short-term fermentation system which had increased different level of aflatoxin B 1 （0, 0.1, 1, 10 μ g/mL）. The result of this study found that the concentrations of NH 3 -N and volatile fatty acid were decreasing following the increasing of aflatoxin B1. The production of volatile fatty acid based on the substrate of maize meal was higher （P〈0.05） than of alfalfa hay. The proportion of acetate, propionate, butyrate and valerate also decreasing according to the increasing the dose of aflatoxin B 1 , and the proportion of isovalerate increasing because of high level of dimethylsulfoxide（DMSO）. Aflatoxin B 1 also caused inhibition the methane production （P〈0.05）. Beside it has ability to inhibit the activity of cellulose. （Conclusion）According to the above results, Itshows clearly that aflatoxin could be inhibition the activity of microorganisms in rumen, especially the fermentation of fibrous feedstuff.