Swine diets impact manure characteristics and gas emissions: Part I sulfur level

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

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2019
Publication Date: 10/15/2019
Citation: Trabue, S.L., Kerr, B.J., Scoggin, K.D. 2019. Swine diets impact manure characteristics and gas emissions: Part I sulfur level. Science of the Total Environment. 687:800-807. https://doi.org/10.1016/j.scitotenv.2019.06.130.
DOI: https://doi.org/10.1016/j.scitotenv.2019.06.130

Interpretive Summary: Sulfur is a key nutrient in swine diets, and its levels are increasing as growers turn to cheaper feed ingredients. Excess S is potentially associated with both odor emissions and animal health. A study was conducted to determine the effect increasing dietary S levels have on swine manure and emissions from those manures. Increased sulfur in the swine diet lowered manure pH, but increased manure solids, nitrogen and sulfur contents. Concentrations of sulfide in manure increase with increasing dietary S levels. Emissions of hydrogen sulfide, phenol compounds and total odor increased with increasing dietary S. Hydrogen sulfide was the dominate odorant and odor tracked with increasing hydrogen sulfide emissions. High concentrations of hydrogen sulfide are a potential health effect during manure agitation and pumping. Information in this report will be of value for growers, engineers, and scientist as they work with feed material with increasing S inclusion rates.

Technical Abstract: Sulfur is a key nutrient associated with both odor and morbidity of animals from swine operations. Sulfur inclusion rates have been increasing as growers turn to cheaper feed ingredients. A study was conducted to determine the effect of increasing dietary S levels in swine diets on DM, pH, C, N, S, VFA, indole, and phenol concentrations in the manure and concentrations/emissions of C, N, and S gases. A total of 24 gilts averaging 152 kg BW were fed diets containing 1,800, 2,850, 3,900, or 6,000 mg/kg total S, as supplied by CaSO4, for 31 d with an ADFI of 3.034 kg/d. Feces and urine were collected after each feeding and added to manure storage containers. At the end of the experiment, pigs were moved out of the room, rooms were cleaned. Manure samples were collected following gentle stirring and headspace air samples taken post three days stirring. Sulfur in the diet lowered manure pH by 0.28 units for each unit percent increase of CaSO4 added, but DM, N, and S all increased by approximately 10% for 0.1% increase in dietary sulfur. Manure ammonia and sulfide levels increased with increasing S levels. There were no significant differences in C or N emissions, but S emissions increased by 8% for each 0.1% increase in dietary sulfur. As determined by odor activity values, overall odor increased with increasing dietary S with both 4-methylphenol and hydrogen sulfide being the main odorants. Odor increased by 2% for each 0.1% increase in dietary sulfur.