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United States Department of Agriculture

Agricultural Research Service

2009 Annual Report

1a.Objectives (from AD-416)
Objective 1 - Determine the influences of diet composition on odor compound, nitrogen, and greenhouse gas emission from manure in beef cattle and swine confinement facilities. Objective 2 - Define the beef cattle feedlot surface conditions affecting microbial activities that minimize the environmental impact of animal manure. Objective 3 - Develop strategies and technologies to reduce ammonia and odor emissions from beef cattle and swine confinement facilities

1b.Approach (from AD-416)
Objective 1 - The hypothesis to be tested is starch, nonstarch carbohydrate, and protein excretion in manure differ by diet, and these compounds are differentially utilized by microorganisms to produce malodorous compounds, ammonia, and greenhouse gases. Multiple experiments will evaluate swine and cattle manure from diets differing in starch, fiber, and crude protein contents from diverse feed sources in order to determine the effects that diet has on.
1)odor compound production and emission,.
2)nitrogen transformation and loss, and.
3)greenhouse gas emission. Manure slurries and soil/manure mixtures mimicking feedlot surfaces will be incubated over time at ambient temperature and analyzed for microbial fermentation products including straight and branched chain volatile fatty acids, aromatic, sulfur-containing, and nitrogenous compounds, alcohols, and the greenhouse gases-methane, carbon dioxide, and nitrous oxide. Follow-up field studies will seek to validate results from the laboratory by monitoring the production and emission of compounds of concern from the production environment. Objective 2 - The hypothesis to be tested is moisture content, the ratio of manure to soil, and the temperature of the feedlot surface are the dominant factors that contribute to an anaerobic microbial environment on the feedlot surface, which produces more offensive odor compounds, enhances detrimental nitrogen transformations, and contributes to greater greenhouse gas production than an inactive or aerobic microbial state. The approach will be to evaluate a range of environmental conditions affecting dominant microbial physiologies (inactive, aerobic, and anaerobic) in multiple manure and soil incubations which vary the manure moisture content, manure to soil content, and temperature. Conditions favoring beneficial microbial activities (N immobilization, odor compound consumption, and nitrification/denitrification) relative to unfavorable activities (ammonia production and emission, odor compound production and accumulation, and greenhouse gas emission) will be targeted for further characterization and ultimately evaluated in field experiments. Objective 3 - The hypothesis to be tested is a combination of plant essential oils and urease inhibitors will limit microbial activities in stored cattle and swine manure that lead to odor compound production, ammonia formation, and greenhouse gas emissions. Once an effective compound, both in least cost and inhibiting properties is selected, it will be evaluated in the laboratory with a urease inhibitor for control of ammonia and odor emissions. This combination of the urease inhibitor and plant oil will also be incorporated into a granule material. The granule will be evaluated in the laboratory for effectiveness in releasing the chemicals from the granule by quantifying volatile fatty acids, urea, and ammonia in cattle manure slurries. Field studies in a cattle feedlot will be conducted with the granule containing the two chemicals. Field studies in an anaerobic deep pit swine production facility without the granule will also be conducted.

3.Progress Report
Ethanol production from corn has resulted in a large quantity of wet distillers grains with solubles (WDGS) which has proven to be a viable feed resource for beef cattle. A study was conducted in 2007 to compare odorants and persistence of generic E. coli and E. coli O157:H7 in manure slurries stored from 0 to 28 days from cattle fed 0, 20, 40, or 60% WDGS. The results from this study with 160 steers on cement floors indicated all the major odorants in the manures significantly increased as the concentration of WDGS increased in the diet. A second study was conducted in 2008 with over 600 animals on a soil-based feedlot surface and fed either 0 or 40% WDGS diets. Both studies, with cattle on different surfaces indicated the odorants ammonia, hydrogen sulfide, and volatile fatty acids increased when WDGS was added to the diet. It is concluded that the higher the concentration of WDGS in the diet for feedlot cattle, the greater the risk is for environmental pollution, irrespective of pen surface.

It is unclear what effect dietary antibiotics have on odor production from manure and their fate once excreted. A swine study was conducted with 160 animals, 80 pigs (8 animals per pen) each fed with or without chlortetracycline for two months, then switched to a diet with or without bacitracin fed the last month before slaughter. Manure samples were incubated at room temperature to initiate anaerobic digestion. The jars were sampled at d 0, 2, 4, 7, 14, 21, and 28, and analyzed for volatile fatty acids, aromatics, total alcohols, lactic acid, hydrogen sulfide, ammonia, pH, dry matter, and antibiotic remaining. Sample analyses are currently being carried out to evaluate odor compounds and whether anaerobic digestion destroys the antibiotics.

No research had been conducted to evaluate gas and odor emissions in deep-bedded beef feedlot facilities. Air samples were collected from two pens in two commercial deep-bedded monoslope barns in NW Iowa (n = 4). Environmental (air temperature & relative humidity, pack temperature, pH, moisture content, and electrical conductivity) and management factors (bedding, cleaning, diets, etc) were recorded and correlated to gas measurements. Data collection continued at 6 week intervals from March 2008 until present. Ammonia emissions from the deep bedded barns are greatest during summer months and lower during winter months. Ammonia emissions are not highly correlated to electrical conductivity of the feedlot surface, depth of the bedded pack, or pack pH, but increase with increasing pack temperature. Data collected at 0, 4, and 10 hours after animals were removed indicated that most of the ammonia volatilized from the surface during the first 4 hours, leaving baseline ammonia emissions. The data collected from this project is the first of its kind and will help quantify ammonia emissions in deep-bedded cattle confinement facilities.

1. Odorant production and generic E. coli from cattle fed distillers grains. A feeding trial was conducted on a cement floor with crossbred steers (n = 160; 434 kg) that were fed a finishing diet containing either 0, 20, 40, or 60% wet distillers grains with solubles (WDGS), a byproduct of ethanol production from corn. A second feeding trial using crossbred finishing steers was conducted on a soil-based floor (n = 603; 425 kg) that contained either 0 or 40% WDGS in the finishing diet. The objectives were to determine what effect WDGS would have on odorants, phosphorus, nitrogen, and generic Escherichia coli (E. coli) concentrations in cattle manure slurries. When WDGS is fed to cattle in place of corn, crude protein and minerals often exceed dietary needs. This may increase nitrogen emission, phosphorus run-off, and odor production. Overall, this is what was observed in the two studies. As the level of WDGS increased in the diet, many of the odorants in the form of volatile fatty acids and aromatic compounds increased in the manure slurries, as did ammonia and hydrogen sulfide. Total nitrogen, phosphorus, and sulfur were all found in higher concentrations in the slurries as the level of WDGS increased in the diet. Therefore, the potential for environmental pollution, including elevated ammonia and odor emissions, and increased phosphorus in run-off is greater when WDGS is included in the diet. These studies also indicated that feeding WDGS can extend the persistence of E. coli in manure slurries.

2. Evaluation of wet distillers grains with solubles in feedlot cattle diets. Wet distillers grains with solubles (WDGS) are a commonly fed ingredient in feedlot diets. This feedstuff has high concentrations of nitrogen (N), sulfur (S), and phosphorus (P), which may contribute to odor production and nutrient excretion from cattle manure. The high fiber content of WDGS may contribute to methane during digestion and affect the animal’s ability to utilize energy for growth. A study was conducted to determine the effects of feedlot cattle diets containing 0, 20, 40, or 60% WDGS on energy retention, methane production, and N, S, and P excretion. Methane production decreased when WDGS was added to the diet. Heat production was not affected by dietary treatment, but energy retention decreased as the level of WDGS increased in the diet. This indicates that finishing cattle fed increasing levels of WDGS in the diet have decreased efficiency of energy utilization which could lead to decreased performance in the feedlot. Cattle fed WDGS also had higher concentrations of odorous compounds in feces than cattle fed corn-based diets. A research project was initiated in 2009 to measure ammonia and hydrogen sulfide emissions from the feedlot surface when growing-finishing cattle are fed diets containing 0 or 30% WDGS. These data will provide valuable information to feedlot producers who routinely use WDGS in feedlot diets.

Review Publications
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 Escherichia coli in manure slurries from cattle fed zero, twenty, forty, or sixty percent wet distillers grains with solubles. Journal of Animal Science 86:3617-3627.

Wells, J., Shackelford, S.D., Berry, E.D., Kalchayanand, N., Guerini, M.N., Varel, V.H., Arthur, T.M., Bosilevac, J.M., Freetly, H.C., Wheeler, T.L., Ferrell, C.L., Koohmaraie, M. 2009. Prevalence and Level of Escherichia coli O157:H7 in Feces and on Hides of Feedlot Steers Fed Diets With or Without Wet Distillers Grains with Solubles. Journal of Food Protection. 72(8):1624-1633.

Spiehs, M.J., Varel, V.H. 2009. Nutrient Excretion and Odorant Production in Manure from Cattle Fed Corn Wet Distillers Grains With Solubles. Journal of Animal Science 87:2977-2984. Online. Journal of Animal Science doi:10.2527/jas.2008-1584.

Last Modified: 4/18/2015
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