In vitro metabolism of mycotoxins by bacterial, protozoal and ovine ruminal fluid preparations

Mycotoxin degradation studies with ovine rumen fluid in vitro have shown that degradation of both aflatoxin B₁ and G₁ was < 10% when added at levels of 1.0 and 10.0 μg ml^-1. However, at these concentrations microbial activity was partially inhibited as determined by the percentage inhibition of digestion of alfalfa hay. T-2 toxin, HT-2 toxin, deoxynivalenol and diacetoxyscirpenol were all degraded by ovine rumen fluid in vitro when added at a level of 10 μg ml^-1. There was no significant degradation of neosolaniol. T-2 toxin (10 μg ml^-1) was degraded to HT-2 toxin (6.0 μg ml^-1) and T-2 triol to (1.5 μg ml^-1) after 12 h incubation. Bacterial and protozoal fractions prepared from ovine rumen fluid were capable of T-2 toxin degradation and, although the protozoal fraction was more active in this respect, it was also the most sensitive to the toxic effects. A cell-free preparation from whole ovine rumen fluid was unable to degrade T-2 toxin. These results support the theory that the rumen plays an important role in conferring a certain degree of toxin resistance in ruminant animals.