Effects of ruminal fermentation, intestinal digestion and fecal contact on the survival of Fusarium graminearum on colonized barley grain

Barley grains were colonized in the laboratory with a mixture of three Fusarium graminearum (FG) strains and processed in five different ways. The survivability of FG on the surface of barley kernels in the rumen, lower digestive tract and after contact with feces was investigated. FG-colonized kernels were placed in nylon bags and incubated in the rumen of three steers for 0, 6, 12 and 24 h. Viability of FG was reduced (P < 0.001) after 6 h and FG was non-viable after 12 h in the rumen. To investigate viability in the lower digestive tract, FG-colonized kernels were placed in nylon bags, passed through the duodenum of three cows and recovered in the feces. No viable FG was found in any of the kernels that passed through the lower digestive tract. FG-colonized kernels were also embedded in cattle feces for 0, 2, 4, 7, 14 and 21 d. FG viability was reduced (P < 0.001) after 2 d and was not detected after 4 d of contact with feces. The likelihood of FG remaining viable after passage through the intestinal tract and excretion in the feces of cattle is exceedingly low.