| A rising concern with feeding high levels of distiller's grain with soluble (DGS) is its high S and N content and the effects it might have on S- and N-containing emissions from gas produced in the rumen and manure. Two trials were conducted with 12 Holstein steers housed in individual environmentally-controlled rooms to monitor gas emissions. Three dietary treatments were fed in trial 1; containing 0% (control), 40%, and 60% DDGS. In trial 2, treatments were the same except the 60% DDGS dietary treatment was replaced with a 40% DDGS diet fortified with 8 ppm Mo and 90 ppm Cu, which will be referred to as 40% DDGS+. The 40% DDGS+ diet served as a potential strategy to mitigate S-containing gas emissions. Each trial was divided into 2 phases; phase 1 of each trial monitored emissions when urine and feces were collected in the same vessel. Phase 2 of each trial monitored emissions while steers were fitted with fecal bags to separate feces from urine. Distiller's grain with soluble increased H2S and NH3 production (P < 0.05) and these emissions were decreased to undetectable levels during phase 2 of each trial compared to emissions generated in phase 1 (P < 0.01). Addition of Mo and Cu in trial 2 tended to decrease H2S emissions when adjusted for S-intake (P = 0.08). In trial 2, the 40% DDGS+ treatment decreased CO2 emissions (P < 0.05) and tended to generate less CH4 emissions compared to the control and the traditional 40% DDGS diet. |
