Swine diets impact manure characteristics and gas emissions: Part II Sulfur source

Authors: Trabue, Steven - Steve; Kerr, Brian; Scoggin, Kenwood

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2019
Publication Date: 6/19/2019
Citation: Trabue, S.L., Kerr, B.J., Scoggin, K.D. 2019. Swine diets impact manure characteristics and gas emissions: Part II Sulfur source. Science of the Total Environment. 698:1115-1124. https://doi.org/10.1016/j.scitotenv.2019.06.272.
DOI: https://doi.org/10.1016/j.scitotenv.2019.06.272

Interpretive Summary: Swine growers are increasingly turning to alternative feed ingredients to lower cost, but many of these cheaper sources have increased concentrations of S in both organic and inorganic forms. A study was conducted to determine how the source of S in the diet affects the manure slurries and gas emissions. Diets tested include the following: standard corn soybean meal (CSBM) diet; standard diet enriched with inorganic sulfur; diet with both inorganic and organic S; and a diet enriched with organic S. Animals fed organic S had a significantly higher excretion of solids and nutrients in manure, whereas, animals fed inorganic sulfur had lower manure pH and higher levels of sulfide. Diets with increased levels of organic sulfur had significantly higher levels of NH3, VFAs, and phenols in manure compared to animals fed standard CSBM diets. Hydrogen sulfide emissions were highest for swine diets with inorganic S, but emissions of volatile organic compounds and volatile sulfur compounds were highest in animals fed organic sulfur diets. Manures of animals fed diets with increased organic S contents were determined to be the most odorous by human panels. Information in this report will be of value for growers, engineers, and scientist as they work with feed material with increasing S inclusion rates both organically and inorganically.

Technical Abstract: Sulfur is a key nutrient associated with hydrogen sulfide (H2S) emissions, odor, and respiratory distress of animals. Due to the potential increases in S levels in swine diets, a feeding trial study was conducted to determine the effect of dietary S source material on manure slurries chemical properties and gas emissions. A total of 24 gilts averaging 139 kg body weight were fed a diet containing either 1.80 g S kg-1 or diets containing 3.50 g S kg-1 feed as supplied by CaSO4, distillers dried grains with solubles (DDGS), or corn feather meal (CFM) with an average daily feed intake of 2.70 kg/d over the 41 d trial. Feces and urine were collected after each feeding and added to manure storage containers. At the end of the study, manure slurries were monitored for gas emissions and chemical properties. ANOVA indicated that S source had a significant effect on excretion of DM, C, N, S in manure. Pigs fed DDGS diets had significantly higher levels of NH3, VFAs, and phenols in manure compared to pigs fed CSBM diets. There were no significant differences in C or N emissions for pigs fed different diets, but S emissions showed trends in higher emissions. Odor and odorant emissions were significant different based on diet with CFM being the most odorous compared to standard CSBM diets. Pigs fed CFM and DDGS had a greater percentage of their chemical odor associated with volatile organic compounds while CSBM diets had greater percentage associated with H2S emissions.