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Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/1/2014 Publication Date: 5/14/2014 Citation: Trabue, S.L., Kerr, B.J. 2014. Emissions of greenhouse gases, ammonia, and hydrogen sulfide from pigs fed standard diets and diets supplemented with dried distillers grains with solubles. Journal of Environmental Quality. 43:1176-1186. Interpretive Summary: To reduce feed cost, swine growers are replacing corn with dried distillers grains (DDGS) in the standard corn-soybean meal diet, but effects of this change on manure composition and gas emissions are unknown. Pigs fed DDGS diets grew the same as those fed the standard diet, but manure from those animals had greater retention of both nitrogen (N) and sulfur (S). Emissions of odor causing gases such as hydrogen sulfide were lower from DDGS manure than from manure associated with the standard diet even though concentrations of sulfides were higher. The gaseous emissions were lower because of increased crusting on DDGS manures. Higher N and P concentrations in DDGS manure will increase the agronomic value of that material if managed properly. This study provides important information on the environmental impacts of substituting DDGS for corn in swine diets to producers, engineers, and regulatory officials. Technical Abstract: Swine growers are increasingly supplementing animal diets with dried distillers grains soluble (DDGS) to offset cost of a typical corn-soybean meal diet. An experiment was conducted to investigate the effects of DDGS diets on both on manure composition and emissions of greenhouse gases (GHG), ammonia, and hydrogen sulfide (H2S). Twenty-four pigs, 103.6 kg initial body weight, were fed either a standard corn-soybean meal diet or corn-soybean meal diet supplemented with 35% DDGS. Pigs were fed twice daily over the 42-day trial, with feed intake body weight gain averaging 2.7 and 0.86 kg/d, respectively. Feces and urine were collected after each feeding and added to manure storage containers. DDGS diets reduced manure pH (P < 0.001), and increased both crust formation (P < 0.001) and dry matter (DM) content (p < 0.01). DDGS manures had increased levels of C (P < 0.002), N (P < 0.003), and S (P < 0.001) over standard diets. The lower manure pH and higher sulfur content of the DDGS diet increased both ammonia (p<0.02) and hydrogen sulfide (p <0.001) contents in the DDGS manures over the control diet. In contrast to manure concentration, emissions of ammonia (p = 0.01) and hydrogen sulfide (p = 0.09) were higher in animals fed control diets, whereas, emission of GHG were not affected by diet. Crusting of the DDGS manures is thought to have reduced emissions of both NH3 and H2S and possibly reduced CH4 emissions. This study demonstrates that diets using co-products from ethanol production can significantly impact manure composition and concentrations of nutrients and lower emissions of ammonia and hydrogen sulfide, which may affect the impact of livestock production on the soil, air, and water environment. |
