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Submitted to: Meeting Abstract
Publication Type: Proceedings Publication Acceptance Date: 11/16/2000 Publication Date: 12/4/2000 Citation: Miller, D.N. 2000. Factors controlling the production and consumption of odor compounds in cattle feedlot soils. Proceedings of Innovative Technologies for Planning Animal Feeding Operations, December 4-6, 2000, Denver, Colorado. p. 71-79. Interpretive Summary: Odors from livestock operations are a complex mixture of compounds produced primarily during animal waste fermentation by microorganisms. Volatile fatty acids (VFAs) and aromatic compounds are particularly potent odor compounds, yet very little is known about the biochemical origin of these compounds and environmental factors controlling their production and consumption. The objectives of these studies were 1) to determine the biochemical origin of odor compounds and factors in the feedlot that control their production, and 2) to monitor microbial odor consumption by feedlot soils when oxygen, nitrate, iron, manganese, or sulfate are available to microbes compared to normal, no-oxygen fermentation. We found that starch proved to be the primary source of VFA odor compounds in mixtures of fresh (<24 hr) and old, dry cattle waste. VFA production was also higher in slurries that contained soil, which helped to minimize the effect of acid produced during fermentation. When oxygen, nitrate, iron, manganese, or sulfate is available, odor consumption varies. Oxygen incubation resulted in 100% odor compound removal within 48 hr. Nitrate proved to be the best when no oxygen was available. Incubation with iron was also good as both the peak VFA content and the persistence of VFAs were less when compared to a standard fermentation. The other alternative treatments, manganese or sulfate, were comparable to or worse than the fermentation treatment. Clearly, the biochemical make-up of the waste, the presence of soil, and the availability of oxygen, nitrate, iron, manganese, or sulfate affect the production of odorous compounds in feedlot wastes. Application of these findings may prove useful for controlling odor emissions from confined livestock operations. Technical Abstract: Odors from livestock operations are a complex mixture of compounds produced primarily during animal waste fermentation by microorganisms. Volatile fat acids (VFAs) and aromatic compounds are particularly potent odor compounds, yet very little is known about the biochemical origin of these compounds an environmental factors controlling their production and consumption. The objectives of these studies were 1) to determine the biochemical origin of odor compounds and factors in the feedlot that control their production and 2) to monitor microbial odor consumption by feedlot soils when oxygen, nitrate, iron, manganese, or sulfate are available to microbes compared to normal, no-oxygen fermentation. We found that starch proved to be the prima source of VFA odor compounds in mixtures of fresh (<24 hr) and old, dry cattle waste. VFA production was also higher in slurries that contained soil, which helped to minimize the effect of acid produced during fermentation. When oxygen, nitrate, iron, manganese, or sulfate is available, odor consumption varies. Oxygen incubation resulted in 100% odo compound removal within 48 hr. Nitrate proved to be the best when no oxyge was available. Incubation with iron also good as both the peak VFA content and the persistence of VFAs were less when compared to a standard fermentation. The other alternative treatments, manganese or sulfate, were comparable to or worse than the fermentation treatment. Clearly, the biochemical make-up of the waste, the presence of soil, and the availabilit of oxygen, nitrate, iron, manganese, or sulfate affect the production of odorous compounds in feedlot wastes. Application of these findings may pro useful for controlling odor emissions from confined livestock operations. |
