Effects of Dietary Treatment on Odor and VOCs Emitted From Swine Manure

Odor and volatile organic compounds (VOCs) emissions associated with swine production facilities are major concerns for the swine industry. Swine manure is one of the major sources of odor from swine operations. Odor control approaches include ration manipulation, improved manure treatment processes, capture and treatment of odorous gases, and improved dispersion. This study was conducted to investigate the effects of a low level of crude protein and low sulfur content in diets of young swine on odor and VOCs emissions from the headspace of swine manure. Small pigs in metabolic stalls were fed twice daily over 28 days with diets containing either 19.36 % crude protein, 7.06 % cellulose and 2,296 mg/kg sulfur (diet B) or 17.83 % crude protein, 6.82 % cellulose and 1,772 mg/kg sulfur (diet H). Three replicate trials were conducted and three pigs were used for each diet. All excreted manure (feces and urine) were collected daily after morning feeding and added to the manure storage vessel designed to hold waste from the same growing pig. Gas samples were collected from the headspace of manure storage container using 85 µm Carboxen/PDMS SPME fibers at the end of each trial and three replicate gas samples were collected for each pig. All samples were analyzed simultaneously for chemicals and odors on a GC-MS-olfactometry system. Statistical analyses were performed to determine the effects on diets on target odorous chemicals and odor. A total of 40 compounds belonging to 14 chemical classes were identified in the headspace of swine manure. A subset of 14 odorous compounds responsible for the characteristic odor of swine manure were selected for statistical analyses. The lower sulfur and crude protein diet was associated with reduced methanethiol (p=0.0686), dimethyl sulfide (p=0.0006), 2,4-dithiapentane (p\u3c0.00001), acetone (p=0.0003), toluene (p=0.0133), 4-methyl phenol (p=0.0745), 4-ethyl phenol (p=0.00004) and skatole (p=0.0002). The total odor (p=0.0262) and some characteristic odors caused by specific gases were also significantly reduced, i.e. ‘sewer’ (H2S) (p=0.0014), ‘acetic’ (acetic acid) (p=0.00001), ‘skunky’ (2,4-dithiapentane) (p=0.0261), ‘onion’ (dimethyl trisulfide) (p=0.0122) and phenolic’ (4-ethyl phenol) (p=0.0168)

Ruminal Fermentation of Propylene Glycol and Glycerol

Bovine rumen fluid was fermented anaerobically with 25 mM R-propylene glycol, S-propylene glycol, or glycerol added. After 24 h, all of the propylene glycol enantiomers and approximately 80% of the glycerol were metabolized. Acetate, propionate, butyrate, valerate, and caproate concentrations, in decreasing order, all increased with incubation time. Addition of any of the three substrates somewhat decreased acetate formation, while addition of either propylene glycol increased propionate formation but decreased that of butyrate. R- and S-propylene glycol did not differ significantly in either their rates of disappearance or the products formed when they were added to the fermentation medium. Fermentations of rumen fluid containing propylene glycol emitted the sulfur-containing gases 1-propanethiol, 1-(methylthio)propane, methylthiirane, 2,4-dimethylthiophene, 1-(methylthio)-1-propanethiol, dipropyl disulfide, 1-(propylthio)-1-propanethiol, dipropyl trisulfide, 3,5-diethyl-1,2,4-trithiolane, 2-ethyl-1,3-dithiane, and 2,4,6-triethyl-1,3,5-trithiane. Metabolic pathways that yield each of these gases are proposed. The sulfur-containing gases produced during propylene glycol fermentation in the rumen may contribute to the toxic effects seen in cattle when high doses are administered for therapeutic purposes

Experimental research on the effects of water application on greenhouse gas emissions from beef cattle feedlots

The effect of water application (e.g., through rainfall or sprinkler system) on emissions of greenhouse gases (GHGs), such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), from pen surfaces of open-lot beef cattle feedlots was evaluated under controlled laboratory conditions. Soil/manure samples were collected from several randomly selected pens from two beef cattle feedlots in Kansas and were used as simulated pen surfaces. Three treatments (i.e., dry and loose, moist and loose, and moist and compacted pen surface conditions) were considered, simulating surface conditions in the field after a typical rainfall event or water application with a sprinkler system. Soil/manure and water were mixed within glass containers and analyzed for GHG emission using a photo-acoustic infrared multi-gas analyzer; emission rates were calculated from measured concentrations. GHG emissions from the dry soil/manure samples were low, with mean values of 0.02, 0.00, and 45 mg m−2 h−1 for N2O, CH4, and CO2, respectively, compared to moist soil/manure samples. Water application on the dry manure samples resulted in large peaks of GHG fluxes, with peak values of 99.2, 28.6, and 15,443 mg m−2 h−1 for N2O, CH4, and CO2, respectively.The effect of water application (e.g., through rainfall or sprinkler system) on emissions of greenhouse gases (GHGs), such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), from pen surfaces of open-lot beef cattle feedlots was evaluated under controlled laboratory conditions. Soil/manure samples were collected from several randomly selected pens from two beef cattle feedlots in Kansas and were used as simulated pen surfaces. Three treatments (i.e., dry and loose, moist and loose, and moist and compacted pen surface conditions) were considered, simulating surface conditions in the field after a typical rainfall event or water application with a sprinkler system. Soil/manure and water were mixed within glass containers and analyzed for GHG emission using a photo-acoustic infrared multi-gas analyzer; emission rates were calculated from measured concentrations. GHG emissions from the dry soil/manure samples were low, with mean values of 0.02, 0.00, and 45 mg m−2 h−1 for N2O, CH4, and CO2, respectively, compared to moist soil/manure samples. Water application on the dry manure samples resulted in large peaks of GHG fluxes, with peak values of 99.2, 28.6, and 15,443 mg m−2 h−1 for N2O, CH4, and CO2, respectively

Field Sampling Method for Quantifying Odorants in Humid Environments

Most air quality studies in agricultural environments use thermal desorption analysis for quantifying semivolatile organic compounds (SVOCs) associated with odor. The objective of this study was to develop a robust sampling technique for measuring SVOCs in humid environments. Test atmospheres were generated at ambient temperatures (23 ± 1.5 °C) and 25, 50, and 80% relative humidity (RH). Sorbent material used included Tenax, graphitized carbon, and carbon molecular sieve (CMS). Sorbent tubes were challenged with 2, 4, 8, 12, and 24 L of air at various RHs. Sorbent tubes with CMS material performed poorly at both 50 and 80% RH due to excessive sorption of water. Heating of CMS tubes during sampling or dry-purging of CMS tubes post sampling effectively reduced water sorption with heating of tubes being preferred due to the higher recovery and reproducibility. Tenax tubes had breakthrough of the more volatile compounds and tended to form artifacts with increasing volumes of air sampled. Graphitized carbon sorbent tubes containing Carbopack X and Carbopack C performed best with quantitative recovery of all compounds at all RHs and sampling volumes tested. The graphitized carbon tubes were taken to the field for further testing. Field samples taken from inside swine feeding operations showed that butanoic acid, 4-methylphenol, 4-ethylphenol, indole, and 3-methylindole were the compounds detected most often above their odor threshold values. Field samples taken from a poultry facility demonstrated that butanoic acid, 3-methylbutanoic acid, and 4-methylphenol were the compounds above their odor threshold values detected most often

Odor Mitigation with Tree Buffers: Swine Production Case Study

Vegetative environmental buffers (VEB) are a potentially low cost sustainable odor mitigation strategy, but there is little to no data supporting their effectiveness. Wind tunnel experiments and field monitoring were used to determine the effect VEB had on wind flow patterns within a swine facility. Particle and odorous compound concentrations were monitored before and after the VEB. Wind tunnel experiments indicated that building orientation had about the same impact on air flow patterns as the combined buildings and VEB. Field monitoring studies revealed that air flow patterns at a swine facility were dynamic showing intense instability during the heat of the day, but stable air in the evening hours indicating that air during the day was controlled by vertical movement into the atmosphere while in the evening air patterns show a collapse mostly horizontal movement. Total particle counts before and after the vegetative buffer were reduced by over 40% and odorous compound concentrations for volatile fatty acids, phenol and indole compounds were reduced by 40–60%. Plant material taken from trees in the vegetative buffer showed no significant loading gradients between materials facing the swine facility and those opposite the swine facility. There were significantly higher loadings of odorous VFAs, phenolic, and indole compounds on plant material for samples taken from 2.7 m compared to samples taken from either 0.6 or 1.3 m indicating that vertical transport was major transport mechanism for odor at the swine facility

Dietary composition and particle size effects on swine manure characteristics and gas emissions

Nutrients excreted from animals affect the nutritive value of manure as a soil amendment as well as the composition of gases emitted from manure storage facilities. There is a dearth of information, however, on how diet type in combination with dietary particle size affects nutrients deposited into manure storage facilities, and how this subsequently affects manure composition and gas emissions. To fill this knowledge gap, an animal feeding trial was performed to evaluate potential interactive effects between feed particle size and diet composition on manure characteristics and manure‐derived gaseous emissions. Forty eight finishing pigs housed in individual metabolism crates which allowed for daily collection of urine and feces were fed diets differing in fiber content and particle size, with their urine and feces collected and stored in 446 L stainless steel containers over a period of 49 d. There were no interactive effects between diet composition and feed particle size on any manure or gas emission parameter measured. In general, diets higher in fiber content increased manure nitrogen (N), carbon (C), and total volatile fatty acid (VFA) concentrations, and increased manure VFA emissions, but decreased manure ammonia emissions. Decreasing the particle size of the diet lowered manure N, C, VFA, phenolics, and indole concentrations, and decreased manure emissions of total VFA. Neither diet composition nor particle size had an impact on manure greenhouse gas emissions (GHG)

Speciation of volatile organic compounds from poultry production

Volatile organic compounds (VOCs) emitted from poultry production are leading source of air quality problems. However, little is known about the speciation and levels of VOCs from poultry production. The objective of this study was the speciation of VOCs from a poultry facility using evacuated canisters and sorbent tubes. Samples were taken during active poultry production cycle and between production cycles. Levels of VOCs were highest in areas with birds and the compounds in those areas had a higher percentage of polar compounds (89%) compared to aliphatic hydrocarbons (2.2%). In areas without birds, levels of VOCs were 1/3 those with birds present and compounds had a higher total percentage of aliphatic hydrocarbons (25%). Of the VOCs quantified in this study, no single sampling method was capable of quantifying more than 55% of compounds and in several sections of the building each sampling method quantified less than 50% of the quantifiable VOCs. Key classes of chemicals quantified using evacuated canisters included both alcohols and ketones, while sorbent tube samples included volatile fatty acids and ketones. The top five compounds made up close to 70% of VOCs and included: 1) acetic acid (830.1 μg m−3); 2) 2,3-butanedione (680.6 μg m−3); 3) methanol (195.8 μg m−3); 4) acetone (104.6 μg m−3); and 5) ethanol (101.9 μg m−3). Location variations for top five compounds averaged 49.5% in each section of the building and averaged 87% for the entire building

Field sampling method for quantifying volatile sulfur compounds from animal feeding operations

Volatile sulfur compounds (VSCs) are a major class of chemicals associated with odor from animal feeding operations (AFOs). Identifying and quantifying VSCs in air is challenging due to their volatility, reactivity, and low concentrations. In the present study, a canister-based method collected whole air in fused silica-lined (FSL) mini-canister (1.4 L) following passage through a calcium chloride drying tube. Sampled air from the canisters was removed (10–600 mL), dried, pre-concentrated, and cryofocused into a GC system with parallel detectors (mass spectrometer (MS) and pulsed flame photometric detector (PFPD)). The column effluent was split 20:1 between the MS and PFPD. The PFPD equimolar sulfur response enhanced quantitation and the location of sulfur peaks for mass spectral identity and quantitation. Limit of quantitation for the PFPD and MSD was set at the least sensitive VSC (hydrogen sulfide) and determined to be 177 and 28 pg S, respectively, or 0.300 and 0.048 μg m−3 air, respectively. Storage stability of hydrogen sulfide and methanethiol was problematic in warm humid air (25 °C, 96% relative humidity (RH)) without being dried first, however, stability in canisters dried was still only 65% after 24 h of storage. Storage stability of hydrogen sulfide sampled in the field at a swine facility was over 2 days. The greater stability of field samples compared to laboratory samples was due to the lower temperature and RH of field samples compared to laboratory generated samples. Hydrogen sulfide was the dominant odorous VSCs detected at all swine facilities with methanethiol and dimethyl sulfide detected notably above their odor threshold values. The main odorous VSC detected in aged poultry litter was dimethyl trisulfide. Other VSCs above odor threshold values for poultry facilities were methanethiol and dimethyl sulfide

Effects of Swine Dietary Treatment on Odor and VOCs Emitted from Swine Manure

Odor and VOCs emissions associated with swine production facilities is a major concern for the swine industry. Swine manure is one of the major sources of odor from swine operations. Odor control approaches include ration manipulation, improved manure treatment processes, capture and treatment of odorous gases, and improved dispersion. This study was conducted to investigate the effects of low level of crude protein and low sulfur content in small swine diet on odor and VOCs emissions from the headspace of swine manure. Small pigs in metabolic stalls were fed twice daily over 28 days with diets containing either 19.36 % crude protein, 7.06 % cellulose and 2,296 mg/kg sulfur (diet B) or 17.83 % crude protein, 6.82 % cellulose and 1,772 mg/kg sulfur (diet H). Three replicate trials were conducted and three pigs were used for each diet. All excreted manure (feces and urine) were collected daily after morning feeding and added to the manure storage vessel designed to hold waste from the same growing pig. Gas samples were collected from the headspace of manure storage container using 85 µm Carboxen/PDMS SPME fibers at the end of each trial and three replicate gas samples were collected for each pig. All samples were analyzed simultaneously for chemicals and odors on a GC-MS-olfactometry system. Statistical analyses were performed to determine the effects on diets on target odorous chemicals and odor. A total of 40 compounds belonging to 14 chemical classes were identified the headspace of swine manure. A subset of 14 odorous compounds responsible for the characteristic odor of swine manure odor were selected for statistical analyses. Lower sulfur and lower crude protein diet was associated with reduced methanethiol (p=0.0686), dimethyl sulfide (p=0.0006), 2,4-dithiapentane (p2S) (p=0.0014), \u27acetic\u27 (acetic acid) (p=0.00001), \u27skunky\u27 (2,4-dithiapentane) (p=0.0261), \u27onion\u27 (dimethyl trisulfide) (p=0.0122) and phenolic\u27 (4-ethyl phenol) (p=0.0168)