ARS | Publication request: Odor and gas emissions and nutrient excretion from pigs fed diets containing dried distillers grains with solubles

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2011
Publication Date: May 14, 2012
Citation: Spiehs, M.J., Whitney, M.H., Shurson, G.C., Nicolai, R.E., Renteria-Flores, J., Parker, D.B. 2012. Odor and gas emissions and nutrient excretion from pigs fed diets containing dried distillers grains with solubles. Applied Engineering in Agriculture. 28(3):431-437.

Interpretive Summary: Over the past decade the ethanol industry in the United States has grown substantially. Competition for corn between the livestock and ethanol industries has increased corn prices. As a result, livestock producers often use the more economical distillers grains as a partial substitute for corn in diets. Diets containing dried distillers grains with solubles (DDGS) are typically higher in nitrogen, phosphorus, sulfur, and fiber than diets containing corn. Previous research has demonstrated that adding fiber to swine diets decreases ammonia emissions. However, the higher nitrogen and sulfur content of DDGS relative to corn may result in increased nitrogen and sulfur excretion in the manure which could contribute to higher ammonia and total reduced sulfur emissions. If phosphorus excretion increases when DDGS are fed, producers may need to increase the amount of land available for manure application in order to properly utilize phosphorus in swine manure. The objective of this study was to determine the effects of adding 20% DDGS to a corn-soybean meal diet on odor, ammonia, and total reduced sulfur concentration from swine manure during the growing-finishing phase. Pigs were fed diets containing 0 or 20% DDGS. Dietary treatment had no effect on total reduced sulfur, ammonia, or odor concentration. Total phosphorus excretion was not affected by dietary treatment, but adding 20% DDGS to the diet increased nitrogen excretion. Therefore, it would appear that producers can feed up to 20% DDGS to growing-finishing swine without negatively affecting air quality.

Technical Abstract: The nutrient composition of corn dried distillers grains with soluble (DDGS) may contribute to the production of odorous compounds from manure of pigs fed diets containing DDGS. A 10-wk trial was conducted to determine odor and gas characteristics of swine manure, and nitrogen and phosphorus balance of growing-finishing pigs fed diets with and without 20% dried distillers grains with solubles (DDGS). Urine and feces from growing-finishing pigs was collected daily, mixed, and emptied into simulated deep pits (SDP) according to respective dietary treatment. Manure accumulated in the SDP during the 10-wk study. Air samples were collected weekly from the headspace above each simulated pit and analyzed for total reduced sulfur (TRS) and ammonia (NH3). Air samples collected during wk 0, 2, 5 and 8 were also evaluated for odor concentration utilizing an odor panel and dynamic forced-choice olfactometery. A phosphorus and nitrogen balance was also conducted. Dietary treatment had no effect on TRS or NH3 emissions, or odor detection threshold (P = 0.17) over the 10-wk trial. The head-space concentration of odor, TRS, and NH3 increased during the 10 wk duration of the study. Total phosphorus excretion was not affected by dietary treatment, but adding 20% DDGS to the diet increased nitrogen excretion.