title: Manure odor potential and Escherichia coli concentrations in manure slurries of feedlot steers fed 40% corn wet distillers grains.
abstract: This study evaluated feeding 0 and 40% wet distillers grains with solubles (WDGS) diets to cattle and the effects on feedlot manure collected from soil-based pens and incubated for 28 d. Steers (n = 603; 261 +/- 32 kg) were fed in eight pens (15 x 150 m) of 75 to 77 steers per pen. Two consecutive experiments were conducted with WDGS--one in which the corn source fed with WDGS was high-moisture and one in which WDGS was fed with dry-rolled corn. We compared odorants (volatile fatty acids [VFAs], aromatic compounds, NH3, H2S) and persistence of Escherichia coli in feedlot manure slurries stored from 0 to 28 d. From both experiments, manure collected from cattle fed 40% WDGS had lower (P < 0.05) total VFAs, including acetate, propionate, and butyrate, all of which continued to be lower to 28 d. However, these slurries had greater concentrations (P < 0.05) of branched-chained VFAs (isobutyrate and isovalerate), especially after 14 d of incubations. Similarly, p-cresol and skatole concentrations tended to be greater in slurries originating from 40% WDGS diets and increased with incubation time. Indole was initially greater in the slurries from 40% WDGS diets; however, it was metabolized by microbes during incubation. Manure slurries from the 40% WDGS diets had greater quantities of H2S, NH3, and P (P < 0.05). Levels of E. coli in 0 and 40% WDGS manure slurries were similar when high-moisture corn was used in the diets. However, when dry-rolled corn was used, E. coli persisted longer in 40% WDGS manure slurries in comparison to 0% WDGS. Results here support earlier studies that suggest feeding WDGS increases odor emissions, N loss, E. coli survival, and surface water contamination due to greater potential P runoff.
authors.affiliation: USDA-ARS, U.S. Meat Animal Research Center, P.O. Box 166, Clay Center, NE 68933-0166, USA. Vince.Varel@ars.usda.gov
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Varel
authors.forename: James E
authors.initials: JE
authors.lastname: Wells
authors.forename: Elaine D
authors.initials: ED
authors.lastname: Berry
authors.forename: Dan N
authors.initials: DN
authors.lastname: Miller
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D004032:Diet / Q000662:veterinary; D004926:Escherichia coli / Q000502:physiology*; D008297:Male; D008372:Manure / Q000032:analysis* / Q000382:microbiology*; D009812:Odorants; D014865:Waste Disposal, Fluid; D003313:Zea mays
chemical_list: D008372:Manure