Manure odor potential and Escherichia coli concentrations in manure slurries of feedlot steers fed 40% corn wet distillers grains

J Environ Qual. 2010 Jul-Aug;39(4):1498-506. doi: 10.2134/jeq2009.0472.

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.

MeSH terms

  • Animal Feed / analysis*
  • Animals
  • Cattle
  • Colony Count, Microbial
  • Diet / veterinary
  • Escherichia coli / physiology*
  • Male
  • Manure / analysis*
  • Manure / microbiology*
  • Odorants*
  • Waste Disposal, Fluid*
  • Zea mays

Substances

  • Manure