Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 4/23/2002
Publication Date: 5/16/2002
Citation: Miller, D.N., Varel, V.H. 2002. The effect of starch, casein, and cellulose additions on odor compound composition and accumulation in cattle feedlots [abstract]. 102nd General Meeting of the American Society for Microbiology, Salt Lake City, UT, pp. 432.
Technical Abstract: The biochemical origin of cattle feedlot odors and the environmental factors controlling their production are not well understood. This study describes the effect of starch, casein, and cellulose substrate additions to slurries of fresh and aged cattle manure on the anaerobic accumulation of fermentation products and the consumption of substrates relative to no addition treatments. Aged cattle manure produced more VFA (245-290 mM) than the fresh manure (91-181 mM) irrespective of substrate additions. In fresh manures, VFA concentrations were higher when carbohydrate (starch or cellulose) was added, whereas starch and protein additions to aged manure increased VFA content relative to no addition controls. Branched-chain VFA and aromatic compounds accumulated only in the aged manure (no addition and protein treatments), indicating that some protein fermentation occurred in those treatments. Starch was the primary source for odor production in both manures; all treatments had losses > 18.6 g/L. Protein losses of 6.9 and 5.5 g/L occurred in the aged manure (no addition and protein treatments, respectively) only after starch was no longer available. Supplementing starch to aged manure eliminated protein fermentation. The production of odorous compounds from manure was controlled by pH and substrate availability, with lactate accumulation modulating pH. Aged manure had greater buffering capacity, likely due to the presence of calcareous soil and the action of lactate-fermenting microorganisms. Substrate additions to manure had little effect on the total production of odor compounds, but it had profound effects on odor compound composition. This study suggests that cattle diet has profound effects on odors, because substrates in the manure determine the composition of odorous products.