Layer Barn Research Articles

Direct Measurement of Greenhouse Gas Emission Rates From Manure Management in Different Livestock Production Systems in Cameroon

ABSTRACTDirect measurements of greenhouse gas emissions from the increasingly intensified African livestock production are important to assess locally available mitigation strategies. As such, measurements were conducted from March to June using static flux chambers to quantify the emission rates of CH4, N2O, and CO2 from manure in poultry and pig production systems in Cameroon. Emissions were measured from two layer barns, two pig facilities, six broiler farms, and one farm with Brahman birds. Mean emission factors inside two layer barns were 0.06–0.21 and 602–958 mg animal−1 h−1 for CH4 and CO2, respectively, and 21–112 µg animal−1 h−1 for N2O. Mean emission factors inside four broiler barns with wood shavings as bedding material were 0.31–1.22 and 355–1884 mg animal−1 h−1 for CH4 and CO2, respectively, and 2.33–1052 µg animal−1 h−1 for N2O. Broiler N2O emissions were 971.38 ± 250.23 and 26.14 ± 30.27 µg animal−1 h−1 from manure underneath a meshed floor barn and a shelter with bare soil, respectively. Emissions from a storage tank with wastewater from a piggery were 8.30 ± 7.36 and 40.41 ± 5.54 mg m−2 min−1 for CH4 and CO2, respectively, and 2.80 ± 1.67 µg m−2 min−1 for N2O. Mean emissions from two outdoor storages of a mixture of poultry and pig manure were 0.76–0.9 and 69–136 mg m−2 min−1 for CH4 and CO2, respectively, and 10–15 µg m−2 min−1 for N2O. Emissions depended highly on manure production and management systems. CH4 emissions were lower from poultry compared to pig manure. Younger layers emitted higher CH4 compared to older layer hens. CH4 emissions were higher from slurry compared to solid manure, whereas N2O emissions were higher from solid compared to slurry manure storages. These findings indicate that mitigation strategies for greenhouse gas emissions should depend not only on the type of gases and manure management systems but also on the animal types and their ages.

Validation of Methods for Assessment of Dust Levels in Layer Barns.

The dust level is included in the animal welfare legislation of the European Union, implying assessment of dust levels during veterinary welfare inspections. This study aimed to develop a valid and feasible method for measuring dust levels in poultry barns. Dust levels were assessed in 11 layer barns using six methods: light scattering measurement, the dust sheet test with durations of 1 h and 2-3 h, respectively, visibility assessment, deposition assessment, and a tape test. As a reference, gravimetric measurements were obtained - a method known to be accurate but unsuitable for veterinary inspection. The dust sheet test 2-3 h showed the highest correlation with the reference method with the data points scattered closely around the regression line and the slope being highly significant (p = 0.00003). In addition, the dust sheet test 2-3 h had the highest adjusted R2 (0.9192) and the lowest RMSE (0.3553), indicating a high capability of predicting the true concentration value of dust in layer barns. Thus, the dust sheet test with a test duration of 2-3 h is a valid method for assessing dust levels. A major challenge is the test duration as 2-3 h is longer than most veterinary inspections. Nevertheless, results showed that potentially, with some modifications to the scoring scale, the dust sheet test may be reduced to 1 h without losing validity.

Piling behaviour in British layer flocks: Observations and farmers` experiences

Smothering of laying hens, defined as death due to suffocation when hens tightly pile together in layer barns, is a well-known problem affecting the British loose-housed layer industry. However, knowledge about mechanisms contributing to piling in British layer flocks remains anecdotal. To understand piling behaviour mechanisms, the behaviour of 27 British loosed-house layer flocks from two farmer organisations (four brown hybrids, twenty large barns with a flock size of median ± SD, 10 175 ± 5721 birds, and seven small mobile barns, flock size: 2000 ± 0 birds) with a history of piling behaviour was observed. Video observations were taken along walls and in the centre of the floor area of the layer barns. The number of piles, pile sizes, pile durations, events preceding piles, and locations where piles started (wall/floor area) were described for one day (08:30–16:00 h) at three times of day (0–4 h, >4–8 h, >8–12 h after lights on) either around 20 weeks or around 30 weeks of flock age. Events preceding piling were analysed using descriptive statistics. The effects of time of day, flock age, laying hen hybrid, the area where piles started, and colony size on the number of piling events, pile sizes, and pile durations were assessed using univariate analysis and linear or generalised linear mixed-effects models in R. In addition, twelve British farmers, a subset of the investigated farms, were interviewed about their experiences with piling and smothering. Interviews were audio-recorded, transcribed, and analysed using qualitative content analysis. In total, 92 piles were detected in the videos, lasting on average 21.9 ± 29.3 min and involving 25 ± 39 hens. Piles were mostly preceded by the attraction of hens to other hen behaviours (63.0%) and bird movements through high animal densities on the floor area (23.0%). Piles occurred significantly more frequently at > 4–8 h compared to > 8–12 h and 0–4 h after lights on. Pile sizes were larger in the floor area centre than along walls and positively correlated with pile durations and the flock sizes. Interview analysis revealed that farmers considered multiple events to be triggers for piling and smothering, including the transfer from the rearing to the laying environment, flight responses, broken routines, gregarious nesting in nests or on the floor area, and other gregarious behaviours such as dustbathing in the centre of the floor area. They reported that the causes of piling and smothering change throughout the flock cycle and time of day.

Comparative life cycle assessment of technologies and strategies to improve nitrogen use efficiency in egg supply chains

A non-trivial challenge along egg supply chains is inefficient use of nitrogen, which may have a combination of negative economic, human/animal health, and environmental implications. A variety of technologies and management strategies have been proposed to improve nitrogen use efficiency (NUE) and reduce emissions at key supply chain stages. This study considered seven scenarios representing NUE strategies: (1) biochar addition to the soil and (2) application of the “4Rs” approach to fertilizer management in feed input production; (3) a reduced crude protein supplemented with synthetic amino acids diet; (4) use of acid scrubbers in poultry barns; (5) biochar addition to stored manure; (6) manure incorporation at the time of land application; and (7) joint application of all strategies. ISO 14044 compliant environmental life cycle assessment (LCA) along with NUE calculations were performed to analyze and compare these mitigation options. The functional unit was one tonne of egg production at the farm gate in Canada. The most significant increase in NUE (13%) resulted from the application of the scrubber in the layer barn. The scrubber also significantly lowered acidifying (21%) and eutrophying (16%) emissions compared to the baseline. The combined application of all strategies increased NUE by 15% compared to the baseline scenario and reduced acidification, global warming, and eutrophication potential, but at the cost of a large increase in energy consumption. Each strategy might be more or less suitable depending on the considered environmental impacts, as well as NUE outcomes. Use of LCA is essential to informed decision making in this context.

Air temperature, carbon dioxide, and ammonia assessment inside a commercial cage layer barn with manure-drying tunnels

Understanding the air temperature distribution, ammonia (NH3) and carbon dioxide (CO2) levels in poultry housing systems are crucial to poultry health, welfare, and productivity. In this study, 4 Intelligent Portable Monitoring Units and 7 temperature sensors were installed inside and between the cages and above 2 minimum ventilation fans of a commercial stacked-deck cage laying hen house in the Midwest United States (425,000 laying hens) to continuously monitor the interior environment over a 6-month period. During cold conditions (March 12th–May 22nd), there was a variation noted, with barn center temperatures consistently being highest in the longitudinal and lateral direction (P < 0.001) and the top floor deck warmer than the bottom floor (P < 0.05). During hotter conditions (May 23rd–July 26th), the interior thermal environment was more uniform than during the winter, resulting in a difference only in the longitudinal direction. The daily CO2 and NH3 concentrations were 400 to 4,981 ppm and 0 to 42.3 ppm among the 4 sampling locations, respectively. Both CO2 and NH3 decreased linearly with increasing outside temperatures. The mean NH3 and CO2 concentrations varied with sampling locations and with the outside temperatures (P < 0.001). For CO2, the minimum ventilation sidewall had lower values than those measured in the barn’s center (P < 0.05) during cold weather, while the barn center and the manure room sidewall consistently measured the highest concentrations during warmer weather (P < 0.05). For NH3, the tunnel ventilation inlet end consistently had the lowest daily concentrations, whereas the in-cage and manure drying tunnel sidewall locations measured the highest concentrations (P < 0.001). Higher NH3 and CO2 concentrations were recorded within the cage than in the cage aisle (P < 0.05). The highest NH3 concentration of 42 ppm was recorded above the minimum exhaust fan adjacent to the manure drying tunnel, which indicated that higher pressure (back pressure) in the manure drying tunnel allowed air leakage back into the production area through nonoperating sidewall fan shutters.

Diurnal and seasonal variations of odor emissions from broiler and cage-layer barns in the Canadian Prairies.

Odor concentrations (OC) and emissions (OE) were measured for a commercial broiler barn and a cage-layer barn in a cold region (the Canadian Prairies). Seasonal OC and OE profiles were plotted by monthly measurements over the course of a year from March 2015 to February 2016, and diurnal profiles were generated by 2-day measurements in cold, mild, and warm seasons, respectively. Seasonal OC and OE varied for both barns; OC was higher in the cold season, but OE was higher in the mild and warm seasons. The broiler barn had higher annual average OC (718 OU m-3) but slightly lower annual average OE (127 OU s-1 AU-1; AU is per 500 kg of body mass) than the layer barn (574 OU m-3 and 140 OU s-1 AU-1). For the layer barn, OC and OE were reduced by 31% and 33% in the cold season and by 30% and 26% in the mild season after manure removal compared with before manure removal. Statistical results showed increased outdoor temperature and ventilation rate (VR) were associated with decreased OC but increased OE for both barns. Finally, both single linear and multi-linear regression models of OE were developed.

Toxic gas and respirable dust concentrations and emissions from broiler and cage-layer barns in the Canadian Prairies.

This study monitored concentrations and emissions of ammonia (NH3), hydrogen sulfide (H2S), and respirable dust for a commercial broiler and a cage-layer barn in the Canadian Prairies over a year between March 2015 and February 2016. Seasonal concentration and emission profiles were acquired by monthly measurements, while diurnal profiles were generated in different seasons. The indoor air quality was evaluated considering both the individual and the additive health effect (respiratory irritation) of the three air pollutants. In winter, both 8-h and 15-min exposure limits (threshold concentrations) of NH3 were exceeded in the broiler barn; the highest additive level was more than two times of the limit. Seasonal average emissions of NH3, H2S, and respirable dust were 57gd-1AU-1, 1.35gd-1AU-1, and 1.99gd-1AU-1, respectively, for the layer barn, all with higher levels in the mild and warm seasons than in the cold season. The emission data were only obtained for the worst-case scenarios (last week of the production cycle) of the broiler barn, with annual averages of 92gd-1AU-1 for NH3, 1.19gd-1AU-1 for H2S, and 4.32gd-1AU-1 for respirable dust, with obvious higher NH3 levels in winter. Additionally, manure removal once every 3-4days for the layer barn reduced NH3 emissions by 62% and 90% in the cold and mild seasons, respectively. This study also found significant negative influence of outdoor T (Tout) on NH3 emissions for the broiler barn but positive impact of Tout on NH3 emissions for the layer barn.

Dispersion modeling of odour, gases, and respirable dust using AERMOD for poultry and dairy barns in the Canadian Prairies

For determining setback distances considering multiple air pollutants, a comprehensive study was conducted to simulate the atmospheric dispersion of odour, ammonia (NH3), hydrogen sulfide (H2S), and respirable dust using an US EPA air dispersion model AERMOD for a commercial dairy, broiler, and cage-layer barn in the Canadian Prairies. The simulation was conducted using five years of meteorological data. Setback distances were determined with the input of varying monthly emission rates of all four air pollutants and odour impact criteria specifically developed for all three odour sources. Results showed the layer barn had the greatest odour impact area (maximum 3023 m for an annual average odour concentration of 0.01 OU m−3) followed by the broiler and dairy barns. Due to the prevailing south wind for all three barns, odour traveled farthest in the north. Using the suggested odour impact criteria by the Government of Saskatchewan defined for all odour sources, maximum setback distances were decreasing from 1941 to 641 m for the layer barn and from 980 to 320 m for the broiler barn along with the increasing of odour concentration (OC) thresholds (1–6 OU m−3), all in the north direction. While for the dairy barn, setback distances were determined only under an OC limit of 1 OU m−3; maximum 205 m in the north and minimum 171 m in the south. Using the newly developed odour impact criteria specifically for the three odour sources, maximum setback distance of 558 m in the north was determined for the layer barn under an odour threshold of 9 OU m−3. Additionally, the results suggest the use of odour impact criteria for determining setback distance rather than using gas/respirable threshold limits set in ambient air quality standards as the former always requires much greater setback distances than the latter.

Diurnal and seasonal variations of greenhouse gas emissions from a commercial broiler barn and cage-layer barn in the Canadian Prairies

Baseline emission values of greenhouse gases were not well established for commercial poultry barns in cold regions, including Canada, due to a lack of well-designed field studies. Emission factors of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), were acquired for a commercial broiler barn and cage-layer barn in the Canadian Prairies climate. Between March 2015 and February 2016, monthly measurements throughout the year for the layer barn and over 6 flocks for the broiler barn, and diurnal measurements in the mild, warm, and cold seasons for both barns were conducted, respectively. The ventilation rate was estimated based on a CO2 mass balance method; thus CO2 emissions were quantified by the CIGR (2002) models. The CH4 and N2O emissions present at low levels from global perspective for both barns; the cold climate proved to be a major reason for the lower CH4 emission from the layer barn. Considerable seasonal effect was observed only for N2O emissions from the broiler barn, and for CH4 and N2O emissions from the layer barn, both with higher emissions in the mild and warm seasons than in the cold season. The big diurnal variations of CO2 emissions for the layer barn demonstrated the uncertainty of the seasonal results by snapshot measurements and correction factors (from −20.9% to −22.5%) were obtained. Besides, the difference of CH4 and N2O concentrations and emissions as well as CO2 concentrations between best-case (the first day after manure removal) and worst-case conditions (the last day before manure removal) was not obvious for the layer barn. Additionally, changes of temperature and ventilation rate were likely to have more impact on N2O emission for the broiler barn and more impact on CH4 emission for the layer barn than on the other two gas emissions, both with positive correlations.

Environmental Sampling Survey of H5N2 Highly Pathogenic Avian Influenza-Infected Layer Chicken Farms in Minnesota and Iowa.

Respiratory secretions, feces, feathers, and eggs of avian influenza-infected hens provide ample sources of virus which heavily contaminate barn and farm environments during a disease outbreak. Environmental sampling surveys were conducted in the Midwestern United States on affected farms during the 2015 H5N2 highly pathogenic avian influenza (HPAI) outbreak to assess the degree of viral contamination. A total of 930 samples were obtained from various sites inside and outside layer barns housing infected birds and tested with real-time reverse transcriptase PCR. The distribution and load of viral RNA in barns in which most birds were dead at the onset of depopulation efforts (high-mortality barns) were compared with those of barns in which birds were euthanatized before excess mortality occurred (normal-mortality barns). A statistically significant difference was seen between cycle threshold (Ct) values for samples taken of fans, feed troughs, barn floors, barn walls, cages, manure-associated locations, barn doors, egg belts, and the exterior of high-mortality vs. normal-mortality barns. In high-mortality barns, sample sites were found to be the most to least contaminated in the following order: cages, manure-associated locations, barn floors, egg belts, feed troughs, barn doors, barn walls, fans, exterior, and egg processing. Significant changes in Ct values over time following HPAI detection in a barn and depopulation of birds on an infected farm were observed for the manure-associated, barn floor, barn wall, and fan sampling sites. These results show that high mortality in a flock as a result of HPAI will increase contamination of the farm environment. The results also suggest optimal sampling locations for detection of virus; however, the persistence of RNA on highmortality farms may delay the determination that adequate sanitization has been performed for restocking to take place.

Relationships between odor properties and determination of odor concentration limits in odor impact criteria for poultry and dairy barns

Livestock odor properties have not been well understood and the role of hedonic tone (HT) in establishing appropriate odor impact criteria has not been investigated. Five odor properties, including odor concentration (OC), intensity (OI), HT, persistence, and character descriptor, were studied for odorous air from a commercial dairy barn, layer barn, and broiler barn by taking measurements in all four seasons. The seasonal OC of the dairy, layer, and broiler barns averaged 447±162OUm−3, 583±216OUm−3, and 766±148OUm−3, respectively. Correspondingly, OI and HT averaged 2.7±0.5 and −2.6±0.5 for the dairy barn, 2.9±0.4 and −2.9±0.5 for the layer barn, and 3.2±0.4 and −3.1±0.4 for the broiler barn. Significant correlations were observed among OC, OI, and HT for all three odors (P<0.01). Increased OC was accompanied by increased OI but decreased HT. The relationships between OC and OI, and between OC and HT were derived in both Weber-Fechner law and Stevens' power law, while the best relationship between OI and HT turned out to be in a cubic polynomial model for the dairy-barn odor and a quadratic polynomial model for the two poultry barn odors. Based on OI-OC and HT-OC relationships in Weber-Fechner law, a reference table of OC limits was generated with 3 set values for OI (0, 1, and 2) and HT (0, −1, and −2) for all three odor sources, which may provide references in establishing appropriate odor impact criteria to meet different land use purposes. The comparison of the OC limits was made using relationships for all odor samples and for odor below 320OUm−3 (OI=3), indicating no significant difference. Slightly lower OCs from the former were suggested for use in stricter odor impact criteria.

Improving energy efficiency in poultry farms through LED usage: a provincial study

Conventional cage layer barns typically exhibit distinct variations in light levels between tiers in cases where lamps are both ceiling mounted and where they are alternated between ceiling-mounted and drop-down fixtures. Light-emitting diodes (LED) offer benefits over traditional lamps including extended life, reduced energy consumption, no flicker and different lamp forms allowing a greater variety of applications; however, the impacts of such lighting systems have not been thoroughly investigated. A review of poultry layer farm energy consumption was conducted in the Canadian province of Nova Scotia and their barn lighting profiles analysed. From this, a 3-month trial was conducted to investigate the potential of replacing conventional lighting with in-cage modular LED lighting. This initial research suggests that there is potential for the application of LED modular lamps to be used within caged systems without negatively impacting bird welfare or performance, but with the benefit of improved energy efficiency.

Emission factors of greenhouse gases from layer and broiler barns in Cameroon

Limited information is available in the literature on greenhouse gas (GHG) quantification from livestock production systems in Africa. Therefore, this project was carried out to generate baseline emission factors of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) from broiler and layer barns with building design typical of Cameroon. Emissions were measured from two broiler barns during the entire production cycles and a layer barn for a limited period using flux chambers. Methane emission factors from the broiler barns with mud and cement floors were 0.96 ± 1.04 and 0.36 ± 0.17 mg bird−1 hr−1 respectively, and 0.76 ± 0.56 mg bird−1 hr−1 from the layer barn with cement floor. Nitrous oxide emission from the broiler barns with mud and cement floors were 12.94 ± 10.11 and 1.68 ± 1.02 mg bird−1 hr−1 respectively, and 0.21 ± 0.28 mg bird−1 hr−1 from the layer barn. Carbon dioxide emission factors from the broiler barns with mud and cement floors were 9327 ± 3508 and 25526 ± 6904 mg bird−1 hr−1 respectively, and 8942 ± 36756 mg bird−1 hr−1 from the layer barn. When scaled per livestock unit (LU), where 1 LU is 500 kg bird weight, CH4 emissions were 0.16 ± 0.17 and 0.06 ± 0.03 g LU−1 hr−1 from the broiler barns, and 0.19 ± 0.14 g LU−1 hr−1 from the layer barn. Nitrous oxide emissions were 2.16 ± 1.69 and 0.28 ± 0.17 g LU−1 hr−1 from the broiler barns, and 0.05 ± 0.07 g LU−1 hr−1 from the layer barn. Broilers reared in management systems with wood shavings on mud floor had relatively high CH4 and N2O emissions compared to broilers on wood shavings and cement floor, with the contrary observed for CO2. The emissions N2O were significantly higher from broiler barns compared to layer barns. Emissions were higher in the mornings compared to later periods of the day. Given the observed results, GHG emission mitigation strategies need to be customised for each building design and management system.

Ammonia concentrations and emission rates at a commercial poultry manure composting facility

Composting facilities are essential parts of most manure-belt (MB) poultry houses in the U.S., but their NH3 concentrations and emission are not well understood. This may affect farm operation safety and limit the development of NH3 mitigation and management strategies. The study aimed to quantify NH3 concentrations and hen-specific emission rates (ER) at a commercial poultry manure composting facility and to understand their diurnal and seasonal variations. Two large tunnel-ventilated composting buildings with twelve 122-cm exhaust fans were chosen as the study site, which received manure from four on-site manure-belt layer barns. The inlet and exhaust NH3 concentrations at the compost building were monitored quasi-continuously for one month per season for two years. Ammonia ERs were calculated based on the NH3 concentrations and building ventilation rates. The average daily mean ± SD of the NH3 concentrations in spring, summer, fall, and winter were 114 ± 20, 144 ± 35, 115 ± 13, and 141 ± 25 ppmv, respectively. Seasonal and diurnal variations existed in both NH3 concentrations and ERs. The daytime NH3 ER was significantly higher than that of night time. These results showed that NH3 emissions from composting facilities are considerably high, and thus mitigation strategies are needed to further reduce NH3 from the whole MB layer facility system.

Identification of Bioaerosols Released from an Egg Production Facility in the Southeast United States

This field study investigated biological characteristics of aerosols emitted from a commercial egg production farm (layer operation). Bioaerosol samples were taken on this farm at five sampling locations covering emission source (inside a layer barn) and four ambient surrounding stations at four wind directions. All-glass impingers (AGI) were used for the field sampling. AGI fluid samples were plated in duplicate on Trypticase Soy Agar for growth of bacteria and Sabouraud Dextrose Agar for growth of fungi. The most prominent bacterial colony types were identified using a combination of methods that include recording characteristics of colony morphology; performing a Gram staining method and metabolic analyses using the Biolog system. Results from thirty-five AGI samples taken at the five stations through seven sampling events over four seasons indicate that there were significantly lower total bacterial concentrations in the samples collected from ambient stations as compared with the samples collected in the layer house; the mean bacterial concentration at the in-house sampling station was 3.86×10(5)±1.74×10(5) cfu/m(3), whereas the mean bacterial concentrations at four ambient stations in the vicinity of the farm ranged from 1.3×10(3) to 6.2×10(3) cfu/m(3) with no significant differences in mean among ambient stations. There were also no significant differences in fungi concentrations among all sampling stations. Mean fungi concentrations at the in-house station was 3.0×10(3)±4.45×10(3) cfu/m(3), whereas the mean concentrations at the ambient stations ranged from 7.4×10(3) to 1.7×10(4) cfu/m(3). The most prominent bacterial species differed among all five stations. Three of the most prominent bacteria from samples taken at all five stations were gram positive. Fungal type also differed from station to station.

Assessment of Long-Term Gas Sampling Design at Two Commercial Manure-Belt Layer Barns

Understanding temporal and spatial variations of aerial pollutant concentrations is important for designing air quality monitoring systems. In long-term and continuous air quality monitoring in large livestock and poultry barns, these systems usually use location-shared analyzers and sensors and can only sample air at limited number of locations. To assess the validity of the gas sampling design at a commercial layer farm, a new methodology was developed to map pollutant gas concentrations using portable sensors under steady-state or quasi-steady-state barn conditions. Three assessment tests were conducted from December 2008 to February 2009 in two manure-belt layer barns. Each barn was 140.2 m long and 19.5 m wide and had 250,000 birds. Each test included four measurements of ammonia and carbon dioxide concentrations at 20 locations that covered all operating fans, including six of the fans used in the long-term sampling that represented three zones along the lengths of the barns, to generate data for complete-barn monitoring. To simulate the long-term monitoring, gas concentrations from the six long-term sampling locations were extracted from the 20 assessment locations. Statistical analyses were performed to test the variances (F-test) and sample means (t test) between the 6- and 20-sample data. The study clearly demonstrated ammonia and carbon dioxide concentration gradients that were characterized by increasing concentrations from the west to east ends of the barns following the under-cage manure-belt travel direction. Mean concentrations increased from 7.1 to 47.7 parts per million (ppm) for ammonia and from 2303 to 3454 ppm for carbon dioxide from the west to east of the barns. Variations of mean gas concentrations were much less apparent between the south and north sides of the barns, because they were 21.2 and 20.9 ppm for ammonia and 2979 and 2951 ppm for carbon dioxide, respectively. The null hypotheses that the variances and means between the 6- and 20-sample data were equal at α = 0.05 (P > 0.05) were accepted for both gases. The results proved that the long-term gas sampling design was valid in this instance and suggested that the gas sampling design in these two barns was one of the best on the basis of available long-term monitoring instrumentation at reasonable cost.

Field Tests of a Particulate Impaction Curtain on Emissions from a High-Rise Layer Barn

Particulate matter (PM) emission rates from two high-rise layer barns (barns 1 and 2) were measured from 1 August 2004 to 31 January 2005. A commercial particulate impaction curtain (PIC) was installed parallel to the first floor sidewalls and upstream of the exhaust fans of barn 2 for PM reduction by impaction. Tapered element oscillating microbalance (TEOM) monitors were used to measure PM10 (PM <10 µm) concentrations of barn 1 exhaust air and before and after the PIC in barn 2. Concentrations of total suspended particulate (TSP) were monitored at each location two to three times per week with a gravimetric sampler. Prior to the six-month full-scale test, a preliminary test of the PIC was conducted at a single continuous sidewall fan of barn 2 for 10 d. Results of the preliminary test indicated that the PIC reduced PM10 emission by 33% to 49% and TSP emission by 62% to 72%. In the full-scale test, average untreated daily mean PM10 emissions were 30 ±13 and 35 ±33 mg d-1 hen-1 (mean ±standard deviation) from barns 1 and 2, respectively. The mean treated PM10 emission rate was 22 ±23 mg d-1 hen-1 and was decreased by 41% based on measurements before and after the PIC. However, some dilution occurred due to backflow through non-operating fans. The TSP emission rate of barn 2 was 27 ±23 g d-1 AU-1, 39% lower than barn 1, which was 44 ±29 g d-1 AU-1. However, some important practical issues currently hinder the use of PIC in high-rise layer barns.

Quality-Assured Measurements of Animal Building Emissions: Particulate Matter Concentrations

Federally funded, multistate field studies were initiated in 2002 to measure emissions of particulate matter (PM) <10 μm (PM10) and total suspended particulate (TSP), ammonia, hydrogen sulfide, carbon dioxide, methane, non-methane hydrocarbons, and odor from swine and poultry production buildings in the United States. This paper describes the use of a continuous PM analyzer based on the tapered element oscillating microbalance (TEOM). In these studies, the TEOM was used to measure PM emissions at identical locations in paired barns. Measuring PM concentrations in swine and poultry barns, compared with measuring PM in ambient air, required more frequent maintenance of the TEOM. External screens were used to prevent rapid plugging of the insect screen in the PM10 preseparator inlet. Minute means of mass concentrations exhibited a sinusoidal pattern that followed the variation of relative humidity, indicating that mass concentration measurements were affected by water vapor condensation onto and evaporation of moisture from the TEOM filter. Filter loading increased the humidity effect, most likely because of increased water vapor adsorption capacity of added PM. In a single layer barn study, collocated TEOMs, equipped with TSP and PM10 inlets, corresponded well when placed near the inlets of exhaust fans in a layer barn. Initial data showed that average daily mean concentrations of TSP, PM10, and PM2.5 concentrations at a layer barn were 1440 ± 182 μg/m3 (n = 2), 553 ± 79 μg/m3 (n = 4), and 33 ± 75 μg/m3 (n = 1), respectively. The daily mean TSP concentration (n =1) of a swine barn sprinkled with soybean oil was 67% lower than an untreated swine barn, which had a daily mean TSP concentration of 1143 ± 619 μg/m3. The daily mean ambient TSP concentration (n = 1) near the swine barns was 25 ± 8 μg/m3. Concentrations of PM inside the swine barns were correlated to pig activity.