Binversie, Elizabeth Y.2014-09-052014-09-052014-04https://hdl.handle.net/11299/165424University of Minnesota M.S. thesis. April 2014. Major: Animal Sciences. Advisors: Dr. Marshall D. Stern Dr. Grant Crawford. 1 computer file (PDF); viii, 54 pages.Dried distillers grains with solubles (DDGS) is an inexpensive feed alternative to corn. Previously, over-inclusion of DDGS has produced toxic concentrations of ruminal hydrogen sulfide (H<sub>2</sub>S) gas, resulting in polioencephalomalacia (PEM), a degenerative brain disease. Production of ruminal H<sub>2</sub>S requires an acidic environment conducive to converting free sulfur to H<sub>2</sub>S in the rumen. Therefore, it was hypothesized that creating a less acidic rumen environment would help mitigate ruminal H<sub>2</sub>S production. Two experiments were conducted to determine the effects of dietary roughage and sulfur on in vitro fermentation with ruminal microbes in continuous culture and batch culture. Six dietary treatments were formulated that paired 3 concentrations of sulfur (0.3, 0.4 and 0.5% of diet DM) with 2 concentrations of roughage (3 and 9% of diet DM) and are as follows: low roughage low sulfur (LRLS), low roughage moderate sulfur (LRMS), low roughage high sulfur (LRHS), moderate roughage low sulfur (MRLS), moderate roughage moderate sulfur (MRMS) and moderate roughage high sulfur (MRHS). A diet comprised of 0% DDGS was used as the control (CON) diet. Roughage had no effect on H<sub>2</sub>S production but it did increase fermenter pH, creating a less acidic environment. In experiment 2, an increase in dietary sulfur caused an increase in total H<sub>2</sub>S production, but there was no direct effect of roughage on total H<sub>2</sub>S production. Higher dietary roughage created a less acidic pH but at the expense of in vitro fermentation, because of the lower total VFA concentration. Further investigation is needed to determine more effective methods of mitigating H<sub>2</sub>S production using dietary manipulation, such as higher inclusion of dietary roughage or use of different roughage sources.en-USBatch cultureContinuous cultureDDGSHydrogen sulfidePolioencephalomalaciaEffects of dietary roughage and sulfur in diets containing corn dried distillers grains with solubles on hydrogen sulfide production and rumen fermentation by rumen microbes in continuous and batch cultureThesis or Dissertation