ARS | Publication request: Effect of feeding wet distillers grains with solubles to beef cattle on air and manure quality

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 5, 2012
Publication Date: July 5, 2012
Citation: Spiehs, M.J., Miller, D.N., Woodbury, B.L., Eigenberg, R.A., Varel, V.H., Parker, D.B. 2012. Effect of feeding wet distillers grains with solubles to beef cattle on air and manure quality. Applied Engineering in Agriculture. 28(3):423-430.

Interpretive Summary: Wet distillers grains with soluble (WDGS) are a by-product of the ethanol industry and are commonly fed to feedlot cattle. Diets containing WDGS are typically higher in nitrogen, phosphorus, and sulfur than comparable diets containing dry rolled corn. This excess nitrogen, phosphorus, and sulfur is excreted in the urine and feces and it may be used by microorganisms on the feedlot surface to produce odorous compounds. The objective of this study was to compare ammonia (NH3) concentration in the air and nutrients and odorous compounds in the manure between cattle fed diets with or without WDGS. Five pens of feedlot cattle were fed diets containing 14-35% WDGS and five pens were fed a corn-based diet with no ethanol byproducts. Air samples were analyzed for NH3 concentration. Manure samples were analyzed for dry matter, pH, volatile solids, odorous compounds, and nutrient composition (nitrogen, phosphorus, and sulfur content). Manure from the surface of feedlots with cattle fed diets containing WDGS had a higher concentration of P and S than pens with cattle fed corn-based diets containing no ethanol byproducts. Producers feeding WDGS to growing-finishing cattle may need to increase the amount of land available for manure application in order to properly utilize manure P from the feedlot. Use of 35% WDGS in beef cattle diets increases ammonia concentration in the air, but does not appear to significantly increase the highly odorous compounds.

Technical Abstract: Air quality is becoming a pressing issue for beef feedlot producers. Feeding practices influence the excretion of starch, fiber, nitrogen (N), and sulfur (S) in manure, thereby affecting nutrient content and the production of ammonia and odorous compounds. Wet distillers grains with solubles (WDGS) are a common and economical ingredient in feedlot diets. WDGS are high in protein, fiber, phosphorus (P) and S but low in starch. The objective of this study was to compare ammonia (NH3) concentration in the air and nutrients and volatile organic compounds (VOC) concentration in manure between two dietary treatments fed to feedlot cattle. Five pens of feedlot cattle were fed diets containing 14-35% WDGS and five pens were fed a corn-based diet with no ethanol byproducts (Control). Each pen had twelve sampling locations (N = 120) where air and manure samples were collected from the feedlot surface. Air samples were analyzed for NH3 concentration. Manure samples were analyzed for dry matter, pH, volatile solids, VOC, and nutrient composition (N, P, and S). Concentrations of P and S in manure and NH3 in the air were higher in pens fed WDGS compared to pens fed the control diet. Concentrations of VOC were similar across both treatments.