Enhanced Reduced Sulfur Emission from Manures of Beef Cattle Fed Disteller's Byproducts

摘要

Reduced sulfur compounds (h_2s and methyl sulfides) are normal products of manure decomposition which are emitted from confined animal feeding operations (CAFO). These compounds not only contribute to nuisance odors, but with recent EPA regulations, h2_s emissions in excess of 100 lbs per day must be reported by the livestock operation. Feeding distiller's byproducts, which can be very high in sulfur, has recently become very common in large feedlots. Two studies were conducted to evaluate the relative impact of feeding wet distiller's grain plus solubles (wdgs), which can be high in sulfur, to beef cattle. In the first study, beef cattle in sixteen small-scale pens were fed varying amounts (0%, 20%, 40%, and 60%) of WDGS. Fresh manure composites were collected four times from each pen during the study, and the relative emissions were measured using a laboratory wind tunnel chamber. The relative emission of reduced sulfur was significantly greater (4 to 22-fold) in the 40% and 60% WDGS manures forall time periods compared to the 0% manure composite. A second follow up study in eight production-scale feedlot pens feeding either 0% or 40% WDGS demonstrated that reduced sulfur emissions were consistently larger (up to 2.6-fold) from the feedlot surface near the feed bunk when cattle were fed the 40% diet. Largest reduced sulfur emissions were detected when the feedlot surface was wet. Spatially, relative emission from the feedlot surface after animals were removed from the pens came principally from the wetter edges of the pen. Taken together, the results indicate that very large CAFO need to consider both the sulfur content and the feeding level of WDGS in order to comply with EPA's reduced sulfur emission guidelines. More intensive manure management of the edges of pens may minimize emissions, but further research is needed to demonstrate whether this management practice is truly effective.