|Parker, David - Former Ars Employee|
Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2014
Publication Date: 1/20/2015
Publication URL: http://handle.nal.usda.gov/10113/60385
Citation: Hales, K.E., Parker, D.B., Cole, N.A. 2015. Volatile organic compound flux from manure of cattle fed diets differing in grain processing method and co-product inclusion. Atmospheric Environment. 100:20-24. Interpretive Summary: Odor and volatile organic compound emissions have been an issue at animal feeding operations, and has become more prevalent as houses encroach upon areas once occupied only by agriculture. These odors are generally caused by odorous volatile organic compounds emitted from manure, the mixture of feces and urine. Wet distillers grains with solubles are a by-product of the ethanol industry in the U.S., and have become a staple in many beef cattle finishing diets. The objective of this research was to determine flux of volatile organic compounds from feces and urine and a mixture of both from cattle fed steam-flaked or dry-rolled corn-based diets with 0% or 30% wet distillers grains with solubles. Flux of sulfurous compounds was greater from feces of cattle fed dry-rolled corn than steam-flaked corn diets. No other differences in flux from feces were detected across dietary treatments for other compounds. Flux of volatile fatty acids from urine was greater for cattle fed steam-flaked corn than dry-rolled corn diets and there were no differences in 0% or 30% wet distillers grains with solubles. Based on these results, the majority of the volatile organic compounds and volatile fatty acid flux from cattle feeding operations is from the urine. Therefore, dietary strategies to reduce odor from cattle feeding facilities should primarily focus on reducing excretion of odorous compounds in the urine.
Technical Abstract: Odor emissions from livestock production have become increasingly important in the past decade. Odors derived from animal feeding operations are caused by odorous VOC emitted from the mixture of feces and urine, as well as feed and silage which may be experiencing microbial fermentation. Distillers grains are a by-product of corn grain fermentation used to produce fuel ethanol, and this industry has grown rapidly throughout the U.S. in past years. Therefore, the use of wet distillers grains with solubles (WDGS) in feedlot cattle diets has also increased. The objective of this research was to determine specific VOC emissions from frozen feces and urine or a mixture of both, from cattle fed steam flaked or dry-rolled corn(DRC)-based diets containing either 0% or 30% WDGS. Flux of dimethyl trisulfide was greater from feces of cattle fed DRC than steam-flaked corn (SFC) diets. No other differences in flux from feces were detected across dietary treatments for phenol, 4-methylphenol, indole, skatole, dimethyl disulfide, and flux of volatile fatty acids (VFA) such as acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids (P > 0.15). Flux of skatole, acetic acid, and valeric acid from urine was greater for cattle fed SFC than DRC diets (P < 0.05). Moreover, dimethyl disulfide flux was greater for cattle fed DRC vs. SFC diets (P = 0.05). When evaluating WDGS inclusion in the diet, flux of acetic acid and heptanoic acid from urine was greater when cattle were fed diets containing 0% WDGS than 30% WDGS (P < 0.05). When combining urine and feces in the ratio in which they were excreted from the animal, flux of propionic acid was greater when cattle were fed DRC vs. SFC diets (P = 0.05). Based on these results, the majority of the VOC, VFA, and odor flux from cattle feeding operations is from the urine. Therefore, dietary strategies to reduce odor from cattle feeding facilities should primarily focus on reducing excretion of odorous compounds in the urine.