Transformation of nivalenol by gastrointestinal microbes

The capacity of the gastrointestinal microflora of pig, cow, and chicken to metabolize nivalenol (NIV) and deoxynivalenol (DON) was studied both in vivo and in vitro. Before feeding NIV to pigs, no metabolites of NIV or DON were formed in anaerobic incubates of the toxins with the pigs feces. However, after one week on a diet containing 2.5 or 5 ppm NIV, nearly all excreted NIV in feces had been de-epoxidated in five of six pigs. After three weeks on the NIV diet also the sixth pig had acquired this ability. Deoxynivalenol was also de-epoxidated when incubated in vitro with the microorganisms that formed de-epoxy-NIV in vivo. Anaerobic incubation of NIV and DON with cow rumen fluid produced de-epoxides of both toxins in a high proportion. No de-epoxide of NIV, but another unidentified metabolite was found in feces from chicken fed 2.5 or 5 ppm NIV for three weeks.