Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 3, 2008
Publication Date: July 23, 2008
Citation: Varel, V.H., Wells, J., Berry, E.D., Spiehs, M.J., Miller, D.N., Ferrell, C.L., Shackelford, S.D., Koohmaraie, M. 2008. Odorant production and persistence of generic E. coli in manure slurries from cattle fed 0, 20, 40, and 60% wet distillers grains with solubles (WDGS)[abstract]. Journal of Animal Science 86(E-Suppl. 2)/Journal of Dairy Science 91(E-Suppl. 1):325. Technical Abstract: Ethanol production from corn removes starch and concentrates the remaining nutrients including CP and minerals. When WDGS are fed to cattle in place of corn, CP and minerals exceed dietary needs. This may increase N emission, P run-off, and odor production. Crossbred steers (n = 160; 434 kg) were assigned in a completely randomized block design to 9 x 9 m pens with concrete floor (10 animals/pen; 4 pens/trt). Steers were fed a finishing diet that contained either 0, 20, 40, or 60% WDGS on a DM basis, and provided 13.4, 14.6, 18.7 or 22.8% CP, respectively. One kg of manure slurry (14 to 23% DM) was collected from each pen (Aug. 20, Sept. 24, and Oct. 22). Samples were analyzed immediately for odorants, DM, pH, ammonia, L-lactate, and level of generic E. coli. After incubation of the samples at 22°C for 2, 4, 7, 10, 14, 21, and 28 d, samples were analyzed for the above parameters plus methane production. Ammonia, reduced sulfur, indole, phenol, isovalerate, isobutyrate and acetate increased (P < 0.01) with increasing amounts of WDGS in the diet. Other odorants, skatole, caproate, valerate, butyrate, and propionate were greater (P < 0.01) in manure slurries from cattle fed either 20 or 40% WDGS, compared to 0% WDGS. L-lactate was greater (P < 0.01) in slurries from cattle fed 0% WDGS (447 µmol/g DM) compared to the other treatment slurries (14-15 µmol/g DM). L-lactate lowered slurry pH (6.3, 7.1, 7.6, and 8.2, respectively, for 0, 20, 40, and 60% WDGS) which inhibited microbial fermentation, generic E. coli persistence, and methane production. Because of the favorable pH in the 40 and 60% WDGS slurries, most of the odorant compounds were rapidly converted to methane during a 28 d static incubation. These data indicate feeding WDGS can increase odorants in manure slurries and extend the persistence of generic E. coli.