Effect of corn processing and wet distiller’s grains with solubles on odorous volatile organic compound emissions from urine and feces of beef cattle

Authors: Spiehs, Mindy; JADERBORG, JEFFREY - University Of Minnesota; Hales Paxton, Kristin; DICOSTANZO, ALFREDO - University Of Minnesota; CRAWFORD, GRANT - Merck Animal Health; Parker, David

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2018
Publication Date: 6/16/2018
Citation: Spiehs, M.J., Jaderborg, J.P., Hales, K.E., DiCostanzo, A., Crawford, G.I., Parker, D.B. 2018. Effect of corn processing and wet distiller’s grains with solubles on odorous volatile organic compound emissions from urine and feces of beef cattle. Applied Engineering in Agriculture. 34(3):591-598. https://doi.org/10.13031/aea.12708.
DOI: https://doi.org/10.13031/aea.12708

Interpretive Summary: Wet distiller’s grains with solubles (WDGS) are a by-product of the ethanol industry and are a common feed ingredient in cattle feedlot diets. While economical to feed, the nutrient content of this feed ingredient do not match the cattle’s nutrient needs well and can provide too much nitrogen to the cattle, which gets excreted in the urine and feces. Microorganisms present in the feces and feedlot surface convert this nitrogen into odorous compounds that negatively impact the air quality around beef cattle feedlots. Other researchers have had success decreasing the odors associated with beef feedlot when high moisture corn was fed instead of dry rolled corn in the diet. This was because the high moisture corn was more digestible and fewer nutrients were excreted in the feces for the microorganisms to ferment into odorous compounds. But the combination of diets containing both high moisture corn and wet distiller’s grains has never been tested. A study was conducted to test diets containing high moisture corn or dry rolled corn in combination with 25% or 45% wet distiller’s grains with solubles in the cattle diet. There were four dietary treatments: high-moisture corn with 25% distiller’s grains, high-moisture corn with 45% distiller’s grains, dry-rolled corn with 25% distiller’s grains, and dry-rolled corn with 45% distiller’s grains. Some individual odorous compounds were higher in the feces and urine of cattle fed the diets containing wet distiller’s grains with solubles, but, overall, there was no significant difference between cattle fed diets containing either grain (high-moisture corn or dry-rolled corn) or either inclusion rate of wet distiller’s grains with solubles (25% or 45%). This indicates that producers can feed either grain in combination with wet distiller’s grains with solubles at inclusion rates of 25% or 45% of the diet without negatively affecting the air quality surrounding the beef feedlot.

Technical Abstract: Wet distiller’s grains with solubles (WDGS) are a common feed ingredient in beef feedlot diets but the high nitrogen content of these diets creates air quality issues, primarily due to the aromatic compounds emitted during protein fermentation. Use of high moisture corn (HMC) instead of dry-rolled corn (DRC) in cattle feedlot diets has been shown to reduce some odors associated with excess starch in cattle feedlot diets. We hypothesized that using HMC in place of DRC in diets containing WDGS would reduce some of the odors associated with WDGS-DRC diets. A 4 × 4 replicated Latin square with a 2 × 2 factorial arrangement of treatments was used. Diets contained either DRC or a 2:1 ratio of HMC and DRC, with WDGS at either 25% or 45% of the diet dry matter resulting in four treatments: DRC-25, HMC-25, DRC-45 and HMC-45. Odorous compounds were measured from feces and urine of cattle fed the four diets. Feces from cattle fed diets containing 45% WDGS had a higher flux of p-cresol (9.42 µg m-3 min-1), 4-ethyphenol (0.04 µg m-3 min-1), and total aromatic compounds (13.56 µg m-3 min-1) compared to feces from cattle fed 25% WDGS (3.38, 0.03, and 6.86 µg m-3 min-1, respectively). Corn processing did not influence fecal odor flux. Urinary flux of odorous compounds was largely unaffected by corn processing method and only p-cresol (9.58 µg m-3 min-1), and total aromatic compounds (11.34 µg m-3 min-1) were higher for cattle fed 45% WDGS compared to cattle fed 25% WDGS (7.65 and 9.12 µg m-3 min-1, respectively for p-cresol and total aromatics). Overall there were no significant differences in odor potential, as determined by odor activity value (OAV), for cattle fed diets containing HMC and DRC with either concentration of WDGS. From these results, we interpret that producers may feed diets containing HMC or DRC in combination with WDGS at inclusion rates up to 45% with only minimal impacts of air quality.