David B. Parker

Multidimensional Gas Chromatography—Olfactometry for the Identification and Prioritization of Malodors from Confined Animal Feeding Operations

Odor profiling efforts were directed at applying to high-density livestock operations some of the lessons learned in resolving past, highly diverse, odor-focused investigations in the consumer product industry. Solid-phase microextraction (SPME) was used for field air sampling of odorous air near and downwind of a beef cattle feedyard and a swine finisher barn in Texas. Multidimensional gas chromatography-olfactometry (MDGC-O) was utilized in an attempt to define and prioritize the basic building blocks of odor character associated with these livestock operations. Although scores of potential odorant volatiles have been previously identified in high-density livestock operations, the odor profile results developed herein suggest that only a very few of these may constitute the preponderance of the odor complaints associated with these environments. This appeared to be especially true for the case of increasing distance from both cattle feedyard and swine barn facilities, with p-cresol consistently taking on the dominant odor impact role with ever increasing distance. In contrast, at- or near-site odor profiles were shown to be much more complex, with many of the well-known lower tier odorant compounds rising in relative significance. For the cattle feedyard at- or near-site odor profiles, trimethylamine was shown to represent a significantly greater individual odor impact relative to the more often cited livestock odorants such as hydrogen sulfide, the organic sulfides, and volatile fatty acids. This study demonstrates that SPME combined with a MDGC-O-mass spectrometry system can be used for the sampling, identification, and prioritization of odors associated with livestock.

Multidimensional Gas Chromatography-Olfactometry for Identification and Prioritization of Malodors from Confined Animal Feeding Operations

Odor profiling efforts were directed at applying to high-density livestock operations, some of the lessons learned in resolving past, highly diverse, odor-focused investigations in the consumer product industry. Multidimensional-GC-Olfactometry was utilized in an attempt to define and prioritize the basic building blocks of odor character associated with representative cattle feedyard and swine feeding operations. Although scores of potential odorant volatiles have been previously identified in high-density livestock operations, the odor profile results developed herein suggest that only a very few of these may constitute the preponderance of the odor complaints associated with these environments. This appeared to be especially true for the case of increasing distance from the cattle feedyard facilities; with para-cresol consistently taking on the preeminent odor impact role with ever increasing distance. In contrast, at or near-site odor profiles were shown to be much more complex; with many of the traditional lower tier odorant compounds rising in relative significance. Surprisingly, for the at or near-site odor profiles, trimethylamine was shown to represent a significantly greater individual odor impact relative to hydrogen sulfide, the organic sulfides and volatile fatty acids; the more often cited target odorants.

Seepage from earthern animal waste ponds and lagoons--an overview of research results and state regulations

Wastewater seepage from earthen animal waste lagoons and storage ponds can contaminate groundwater with nutrients and pathogens. For almost 30 years, the subject has been the focus of laboratory and field research projects designed to (1) measure if and how much earthen ponds and lagoons leak, (2) determine how different soil types affect seepage rates, and (3) evaluate the magnitudes and mechanisms of sealing from animal waste. In this article we present a research review performed to determine how researchers have attempted to answer these questions and how well they have been answered. We discuss weaknesses in the body of knowledge and present further research and educational needs. We also performed a review of 14 state regulations to assess and compare how different states govern seepage from ponds and lagoons. Six states regulate the maximum allowable seepage rate from ponds and lagoons (values ranging from 0.042 to 0.63 cm/day) while another six states regulate the maximum hydraulic conductivity of earthen liners (values ranging from 0.086 to 0.0086 cm/day). The two remaining states regulate neither. The results of this research and regulatory review demonstrate that there is still much to be learned about seepage from animal waste ponds and lagoons. We suggest that a risk-based approach to regulating seepage may be appropriate in the future.

Recovery of agricultural odors and odorous compounds from polyvinyl fluoride film bags.

Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human panelists using dynamic triangular forced-choice olfactometry. The purpose of this research was to simultaneously quantify and compare recoveries of odor and odorous compounds from both commercial and homemade PVF sampling bags. A standard gas mixture consisting of p-cresol (40 μg m−3) and seven volatile fatty acids: acetic (2,311 μg m−3), propionic (15,800 μg m−3), isobutyric (1,686 μg m−3), butyric (1,049 μg m−3), isovaleric (1,236 μg m−3), valeric (643 μg m−3), and hexanoic (2,158 μg m−3) was placed in the PVF bags at times of 1 h, 1 d, 2 d, 3 d, and 7 d prior to compound and odor concentration analyses. Compound concentrations were quantified using sorbent tubes and gas chromatography/mass spectrometry. Odor concentration, intensity, and hedonic tone were measured using a panel of trained human subjects. Compound recoveries ranged from 2 to 40% after 1 h and 0 to 14% after 7 d. Between 1 h and 7 d, odor concentrations increased by 45% in commercial bags, and decreased by 39% in homemade bags. Minimal changes were observed in intensity and hedonic tone over the same time period. These results suggest that PVF bags can bias individual compound concentrations and odor as measured by dynamic triangular forced-choice olfactometry.

Odor and Odorous Chemical Emissions from Animal Buildings: Part 6. Odor Activity Value

There is a growing concern with air and odor emissions from agricultural facilities. A supplementary research project was conducted to complement the U.S. National Air Emissions Monitoring Study (NAEMS). The overall goal of the project was to establish odor and chemical emission factors for animal feeding operations. The study was conducted over a 17-month period at two freestall dairies, one swine sow farm, and one swine finisher facility. Samples from a representative exhaust airstream at each barn were collected in 10 L Tedlar bags and analyzed by trained human panelists using dynamic triangular forced-choice olfactometry. Samples were simultaneously analyzed for 20 odorous compounds (acetic acid, propanoic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, hexanoic acid, heptanoic acid, guaiacol, phenol, 4-methylphenol, 4-ethylphenol, 2-aminoacetophenone, indole, skatole, dimethyl disulfide, diethyl disulfide, dimethyl trisulfide, hydrogen sulfide, and ammonia). In this article, which is part 6 of a six-part series summarizing results of the project, we investigate the correlations between odor concentrations and odor activity value (OAV), defined as the concentration of a single compound divided by the odor threshold for that compound. The specific objectives were to determine which compounds contributed most to the overall odor emanating from swine and dairy buildings, and develop equations for predicting odor concentration based on compound OAVs. Single-compound odor thresholds (SCOT) were statistically summarized and analyzed, and OAVs were calculated for all compounds. Odor concentrations were regressed against OAV values using multivariate regression techniques. Both swine sites had four common compounds with the highest OAVs (ranked high to low: hydrogen sulfide, 4-methylphenol, butyric acid, isovaleric acid). The dairy sites had these same four compounds in common in the top five, and in addition diethyl disulfide was ranked second at one dairy site, while ammonia was ranked third at the other dairy site. Summed OAVs were not a good predictor of odor concentration (R2 = 0.16 to 0.52), underestimating actual odor concentrations by 2 to 3 times. Based on the OAV and regression analyses, we conclude that hydrogen sulfide, 4-methylphenol, isovaleric acid, ammonia, and diethyl disulfide are the most likely contributors to swine odor, while hydrogen sulfide, 4-methyl phenol, butyric acid, and isovaleric acid are the most likely contributors to dairy odors.

Chemical Composition of Pen Surface Layers of Beef Cattle Feedyards1

The biological, physical, and chemical characteristics of beef cattle feedyard pen surfaces may affect nutrient transformations and losses to the atmosphere, ground water, or surface water. Feedyard pen surfaces can typically segregate into 3 or 4 layers. The purpose of this study was to determine if there were seasonal, within-pen location, days-on-feed, or urine effects on the chemical composition of the pen surface layers of feedyards. Samples were collected from 5 locations in 9 pens at 3 feedyards in each season and were analyzed for gravimetric water, pH, electrical conductivity (EC), nitrate + nitrite-N (NOx-N), ammonia + ammonium-N (NHx-N), N, C, and P. The percentage of water increased (P < 0.01) with depth among the manure layers and decreased in the soil. The pH of the manure layers increased with depth (P < 0.01) from approximately 7.6 to 8.2. The EC of the manure layers was greater (P < 0.01) than the EC of the soil layer, whereas the NOx-N concentration was greater (P < 0.01) in the soil layer. The NHx-N concentrations were lowest in the soil layer (P < 0.01). Total C and N concentrations decreased (P < 0.01) with sample depth. The composition of the layers was affected by season and location within the pen. Recent urine deposition did not affect the lower layers. The NHx-N concentration of the layers increased with days on feed. The differences in the chemical and physical properties of the layers in a feedlot pen may potentially affect nutrient losses to the atmosphere and to groundwater.

Effects of aerosolized feedyard dust that contains natural endotoxins on adult sheep

OBJECTIVE To determine the clinical, clinicopathologic, and histologic effects of aerosolized feedyard dust that contains natural endotoxins on adult sheep. ANIMALS Eighteen 3-year-old Saint Croix sheep. PROCEDURE A prospective randomized controlled study was conducted. There were 2 treatment groups (dust-endotoxin group, n = 9; control group, 9). Aerosolized feedyard dust was provided continuously during a 4-hour period for each application (once in week 1, 3 times in week 2, and 7 times in week 3) to sheep in a semiairtight tent. All sheep were euthanatized and necropsied 8 hours after the treatment group received the last dust treatment. Variables measured before and after each dust treatment were rectal temperature, total WBC count, and concentrations of fibrinogen and haptoglobin. RESULTS Mean amount of dust administered during each treatment was 451 g/4 h. Filter collection indicated 51 mg of dust/m3 and 7,423 ng of endotoxin. Mean rectal temperature at 8 hours (40.4 C) and mean WBC counts 12 and 24 hours after dust treatment were significantly higher for the treated group than the means of the respective variables for the control group. Similar responses were observed with repeated dust-endotoxin treatments; however, with each subsequent treatment, there was a diminished response. Sheep in the treatment group had generalized alveolar septal thickening and hypercellularity. CONCLUSIONS AND CLINICAL RELEVANCE Feedyard dust induced a temporary febrile response and leukocytosis in sheep in the treatment group. Exposure to dust that contains endotoxins may be a stressor preceding acute infectious respiratory tract disease of marketed sheep.

Reduction of Odor and VOC Emissions from a Dairy Lagoon

Odor is a concern at many large animal feeding operations. Due to complaints from downwind neighbors, a project was initiated to reduce emissions of odor and volatile organic compounds (VOCs) from a 3000-cow dairy. An initial odor evaluation showed that the volatile solids loading rate to the lagoons was 15 times that recommended by ASABE standards, and that the primary source of the odor problem was the two lagoons. Abatement measures included covering the treatment lagoon, adding additional aeration capacity to the storage lagoon, and reducing the volatile solids loading rate to both lagoons. Odor, hydrogen sulfide, and water quality were monitored initially and at the completion of the project. A laboratory-based wind tunnel and gas chromatographic method was developed to evaluate reduction in VOC emissions of phenol,4-ethylphenol, p-cresol, indole, skatole, and seven volatile fatty acids. Dramatic improvements in ambient air quality were observed after 30 months, with 80% reduction in ambient odor concentrations and 96% reduction in ambient H2S concentrations downwind of the lagoons. There was a 94.2% reduction in total odorous VOC emissions from the lagoons as measured under laboratory conditions with the small wind tunnel. Paralleled improvements in water quality were observed, with a 55.3% reduction in BOD5, 84.1% reduction in VFAs, and 76.3% increase in oxidation reduction potential (ORP). These results demonstrate the potential for air quality improvements with best management practices such as lagoon covers, aeration, and using innovative methods for reducing the volatile solids loading rate. Relative improvements are always site specific.

Odor and Odorous Chemical Emissions from Animal Buildings: Part 4—Correlations Between Sensory and Chemical Measurements

This study supplemented the National Air Emissions Monitoring Study (NAEMS) with one year of comprehensive measurements of odor emission at five swine and four dairy buildings. The measurements included both standard human sensory measurements using dynamic forced-choice olfactometry and chemical analysis of the odorous compounds using gas chromatography-mass spectrometry. In this article, multilinear regressions between odor and gas concentrations (a total of 20 compounds including H2S, NH3, and VOCs) were investigated. Regressions between odor and gas emission rates were also tested. It was found that gas concentrations, rather than emission rates, should be used to develop multilinear regression models. For the dairy sites, H2S, NH3, acetic acid, propanoic acid, 2-methyl propanoic, and pentanoic acids were observed to be the compounds with the most significant effect on sensory odor. For the swine sites, in addition to these gases, higher molecular weight compounds such as phenol, 4-methyl phenol, 4-ethyl phenol, and 1H-indole were also observed to be significant predictors of sensory odor. When all VOCs were excluded from the model, significant correlations between odor and H2S and NH3 concentrations were still observed. Although these coefficients of determination were lower when only H2S and NH3 were used, they can be used to predict odor variability by up to 83% when VOC data are unavailable.

Reducing odorous VOC emissions from swine manure using soybean peroxidase and peroxides

The objective of the research was to determine the optimum application rates of soybean peroxidase (SBP) plus peroxide (SBPP) for reducing odorous VOC emissions from swine manure. Industrial-grade SBP was applied in combination with liquid hydrogen peroxide (H(2)O(2)) or powdered calcium peroxide (CaO(2)) to standard phenolic solutions and swine manure, and emissions were measured in a wind tunnel. The primary odorant in the untreated manure was 4-methylphenol, which accounted for 68-81% of the odor activity value. At the optimum application rate of SBPP (50 g L(-1)), 4-methylphenol emissions were reduced from the swine manure by 62% (H(2)O(2)) and 98% (CaO(2)) after 24h (P<0.0001). The CaO(2) had a longer residence time, remaining effective for 48 h with 92% reduction in emission rates (P<0.0001), while H(2)O(2) was similar to the control at 48 h (P=0.28).