Reducing ammonia emissions from laying-hen houses through dietary manipulation

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1 This article was downloaded by: [Hongwei Xin] On: 31 January 2012, At: 18:21 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Journal of the Air & Waste Management Association Publication details, including instructions for authors and subscription information: Reducing ammonia emissions from laying-hen houses through dietary manipulation Hong Li a, Hongwei Xin b, Robert T. Burns c, Stacey A. Roberts d, Shuhai Li e, James Kliebenstein f & Kristjan Bregendahl g a Department of Animal & Food Sciences, University of Delaware, Newark, DE, USA b Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA c The University of Tennessee Extension, The University of Tennessee, Knoxville, TN, USA d Akey Nutrition and Research Center, Lewisburg, OH, USA e Renewable Energy Training Center, SUNY Morrisville, NY, USA f Department of Economics, Iowa State University, Ames, IA, USA g Sparboe Farms, Litchfield, MN, USA Available online: 31 Jan 2012 To cite this article: Hong Li, Hongwei Xin, Robert T. Burns, Stacey A. Roberts, Shuhai Li, James Kliebenstein & Kristjan Bregendahl (2012): Reducing ammonia emissions from laying-hen houses through dietary manipulation, Journal of the Air & Waste Management Association, 62:2, To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

2 TECHNICAL PAPER Reducing ammonia emissions from laying-hen houses through dietary manipulation Hong Li, 1 Hongwei Xin, 2, Robert T. Burns, 3 Stacey A. Roberts, 4 Shuhai Li, 5 James Kliebenstein, 6 and Kristjan Bregendahl 7 1 Department of Animal & Food Sciences, University of Delaware, Newark, DE, USA 2 Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA 3 The University of Tennessee Extension, The University of Tennessee, Knoxville, TN, USA 4 Akey Nutrition and Research Center, Lewisburg, OH, USA 5 Renewable Energy Training Center, SUNY Morrisville, NY, USA 6 Department of Economics, Iowa State University, Ames, IA, USA 7 Sparboe Farms, Litchfield, MN, USA Please address correspondence to: Hongwei Xin, 3204 NSRIC, Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50010, USA; hxin@iastate.edu Feed additives can change the microbiological environment of the animal digestive track, nutrient composition of feces, and its gaseous emissions. This 2-yr field study involving commercial laying-hen houses in central Iowa was conducted to assess the effects of feeding diets containing EcoCal and corn-dried distillers grain with solubles (DDGS) on ammonia (NH 3 ), hydrogen sulfide (H 2 S), and greenhouse gas (CO 2,CH 4, and N 2 O) emissions. Three high-rise layer houses (256,600 W-36 hens per house) received standard industry diet (Control), a diet containing 7% EcoCal (EcoCal) or a diet containing 10% DDGS (DDGS). Gaseous emissions were continuously monitored during the period of December 2007 to December 2009, covering the full production cycle. The 24-month test results revealed that mean NH 3 emission rates were , , and g/hen/day for the EcoCal, DDGS, and Control diet, respectively. Namely, compared to the Control diet, the EcoCal and DDGS diets reduced NH 3 emission by an average of 39.2% and 14.3%, respectively. The concurrent H 2 S emission rates were , , and mg/ hen/day for the EcoCal, DDGS, and Control diet, respectively. CO 2 emission rates were similar for the three diets, , , and g/hen/day for EcoCal, DDGS, and Control, respectively (P ¼ 0.45). The DDGS and EcoCal houses tended to emit less CH 4 than the Control house (0.16 and 0.12 vs g/hen/day) during the monitored summer season. The efficacy of NH 3 emission reduction by the EcoCal diet decreased with increasing outside temperature, varying from 72.2% in February 2009 to 7.10% in September Manure of the EcoCal diet contained 68% higher ammonia nitrogen (NH 3 -N) and 4.7 times higher sulfur content than that of the Control diet. Manure ph values were 8.0, 8.9, and 9.3 for EcoCal, DDGS, and Control diets, respectively. This extensive field study verifies that dietary manipulation provides a viable means to reduce NH 3 emissions from modern laying-hen houses. Implications: This work demonstrated that dietary manipulation can be used to reduce NH 3 emissions from high-rise laying-hen houses with no adverse effect on the hen production performances (to be presented separately). The NH 3 reduction rates could vary with different climates and hence geographic locations. The dietary manipulation to lower NH 3 emissions should be applicable to all egg production systems. The results of this study also contribute to the baseline data for improving the national air emissions inventory for livestock and poultry production facilities. Introduction Gaseous emissions associated with animal feeding operations (AFOs) have been an issue of concern because of their negative impacts on the environment. Aerial ammonia (NH 3 ), hydrogen sulfide (H 2 S), and greenhouse gas (GHG) (CO 2,CH 4, and N 2 O) emissions from the production facilities receive the most attention. NH 3 emission is an environmental concern because of its Journal of the Air & Waste Management Association, 62(2): , Copyright 2012 A&WMA. ISSN: print DOI: / contribution to soil and water acidification and increased nitrogen deposition in ecosystems. NH 3 is also a precursor to secondary particulate matter (PM) in that it contributes to the formation of PM through a series of gas- and aqueous-phase chemical reactions with nitrogen oxides (NO x ) and/or sulfur oxides (SO x ). NH 3 from animal agriculture has been estimated to represent the largest portion of the national NH 3 emissions inventory in the United States (U.S. Environmental Protection

3 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Agency). Excessive NH 3 in poultry housing also adversely affects bird health and production performance. Atmospheric NH 3 concentration in poultry houses is generally recommended to be lower than 25 ppm to ensure occupational and bird health (United Egg Producers, 2010). NH 3 is produced as a by-product of the microbial decomposition of organic nitrogenous compounds in feces and urine. The volatilization of NH 3 can be highly variable, depending on total NH 3 concentration, temperature, ph, and storage time of manure (Li and Xin, 2010). Although baseline emission data are important and considerable progress has been made in collection of such data, devising practical solutions to mitigate air emissions remains the ultimate goal for the animal industry to address air quality-related environmental issues (Liang et al., 2005). Several approaches have been investigated and, in some cases, adopted to reduce NH 3 emissions from animal housing, i.e., dietary manipulation, manure treatment, and exhaust air treatment. The U.S. egg industry has been proactively looking for practical means to reduce NH 3 generation and/or emissions from egg production facilities. Dietary manipulation, as one of the NH 3 -lowering methods, has great promise. Nitrogen (N) content in feces and urine is influenced by feed composition and feed conversion efficiency of the birds. Dietary strategies aimed at nutrient reduction, particularly dietary protein content, can result in a reduction of NH 3 formation. Feeding reduced protein diets can lower nitrogen (N) excretion and subsequent NH 3 volatilization (Liang et al., 2005; Sutton et al., 2001). Roberts et al. (2007) reported considerable reduction of NH 3 emission from laying-hen manure fed fibrous diets (including corn-dried distillers grain with solubles [DDGS]). Diets containing acidifier ingredient (e.g., EcoCal a mixture of natural zeolite and gypsum) have been shown to lower NH 3 emission from laying-hen manure (Wu-Haan et al., 2007). Most studies were done under laboratory conditions that involved small number of animals and for relatively short periods. Hence, field verification and demonstration of the promising dietary strategies are needed before consideration of their wider adoption by the egg industry. A 2-yr field study was conducted in Iowa to verify the efficacy of NH 3 emissions reduction by feeding EcoCal or DDGS to laying hens in commercial high-rise houses. This article focuses on the gaseous emissions and manure properties as affected by the dietary regimens. A separate paper is prepared and expected to be published that addresses the hen production performance (not adversely affected by the dietary regimens) and analysis of the economic efficiency. Materials and Methods Housing characteristics and management practices This project was conducted with three commercial high-rise (HR) laying-hen houses located in central Iowa, each measuring m (width length) with a housing capacity of 256,600 Hy-Line W-36 hens. The total hen population was provided by the cooperative producer and daily mortality was considered in the determination of hen population in each house for a given day. Each house had m-diameter exhaust fans along the sidewalls of the manure storage level, providing negative-pressure cross ventilation (Figures 1 and 2). Manure first fell onto the dropping boards below the cages and was then mechanically scraped into the underneath storage four times a day (06:30 a.m., 09:00 a.m., 12:00 p.m., 03:00 p.m.). A photoperiod of 16:8 light:dark (L:D) was generally used except during the molting period. The three houses received one of three diets, namely, a diet containing 7% (by weight) EcoCal (EcoCal), a diet containing 10% (by weight) corn DDGS (DDGS), and a control diet (Control). Metabolizable energy (ME) and crude protein (CP) levels of the three regimens from 26 to 85 weeks of age are listed in Table 1. CP was same for all three diets in a given feeding phase. ME in the DDGS diet was slightly lower than that of the Control diet (13.5 vs MJ/kg). Because of the proprietary nature of the dietary formulation, other compositions of the diets could not be disclosed. At the onset of the monitoring on December 6, 2007, hens for the dietary regimens had the following ages: 41 weeks for EcoCal, 30 weeks for Control, and 19 weeks for DDGS. Monitoring of all the houses started following a complete removal of manure in the lower-level storage. Molting started on June 30, 2008, in the EcoCal house, on September 14, 2008, in the Control house, and on December 27, 2008, in DDGS house (at age of 72 to 75 weeks). A molting diet was used during the molting period. The EcoCal house was depopulated during May 13 21, 2009, and restocked by June 9, 2009; the new flock in this house was fed the DDGS diet. The Control house was depopulated during July 16 24, 2009, and restocked by August 6, 2009; the new flock was fed the EcoCal diet. Finally, the DDGS house was depopulated during November 6 18, 2009, and restocked by December 17, 2009; and the new flock was fed the Control diet. Assigning different diets to the new flocks was to minimize potential house effect, even though the houses were identical in structure and environmental control systems. A mobile air emissions monitoring unit (MAEMU) housing the measurement and data acquisition systems was installed on site and used to continuously collect data on NH 3,H 2 S, and carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) emissions from the three laying-hen houses. The MAEMU had been successfully used for monitoring air emissions from animal housing (Li and Xin, 2010). A brief description of MAWMU is provided here. A photoacoustic multigas analyzer (INNOVA model 1412; INNOVA AirTech Instruments A/S, Ballerup, Denmark) was used to measure NH 3,CO 2,CH 4, and N 2 O concentrations and dew-point temperature, whereas an ultraviolet (UV) fluorescence H 2 S analyzer (model 101E; Teledyne API, San Diego, CA) was used to measure H 2 S concentrations. The gas analyzers were checked with calibration gases weekly, and recalibrated as needed. Initially, the multigas analyzer was only equipped with optical filters for NH 3,CO 2, and dew-point measurement prior to June The analyzer was reconfigured with an additional CH 4 filter in June Air samples were drawn from two composite locations (east and west sections) in each house as well as from an inlet location in the ceiling of one house to provide the ambient background data. Each composite air sample was drawn from two sampling ports (north and south side) near the continuously running

4 162 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Figure 1. Schematic layout of air sampling ports in the high-rise laying-hen houses monitored. Figure 2. Cross-section view of the monitored high-rise laying-hen houses and sampling locations. (minimum) ventilation fans (40 m from end wall) in the manure storage level. Placement of the air sampling ports and the air temperature sensors in the manure storage level were as follows: 1.2 m away from the exhaust fan in the axial direction, 2.7 m from the center in the radial direction, and 1.2 m above the floor. Sampling locations and placement of the sampling ports were chosen to maximize representation of the air leaving the houses. Each sample inlet point was equipped with dust filters to keep large particulates from plugging or contaminating the sample line, the servo valves or the delicate measurement instruments. A positive-pressure gas sampling system (PP GSS) was used in the MAEMU to eliminate or minimize introduction of unwanted air into the sampling line. The PP GSS continuously pumped sample air from each location using individual, designated pumps. The sample air was bypassed when not analyzed. Air samples from each location were collected sequentially over 2-min period via the controlled operation of the servo values of the PP GSS. Every 2 hr, air sample from the ambient (background)

5 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Table 1. Metabolizable energy (ME) and crude protein (CP) levels (dry matter) of the laying-hen diets from 26 to 85 weeks of age Mean* location was drawn and analyzed for 8 min. The last 30 sec concentration readings of the 2-min or 8-min sampling period were used as the measured values. Linear interpolation from the two adjacent measured values at each location was used to determine the intermediate concentration values and aligned with the continuously measured ventilation rate (VR) for the location. Ventilation rates (VRs) of the houses were measured using the following procedure. Due to the high number of fans (72 fans per house in seven stages), 15 fans (minimum ventilation stage) during each fall and 26 fans (minimum stage plus two randomly selected fans from each stage above minimum stage) during each spring were selected and calibrated in situ, individually and in combined operational stages. The in situ calibration of the exhaust fans was conducted with two fan assessment numeration system (FANS) units, from which an overall ventilation curve (airflow rate vs. static pressure) for each house was established by using regression with pooled data points, namely, VR ¼ D ða SP 2 þ b SP þ cþ (1) where VR is air flow rate, m 3 /hr; SP is static pressure, pa; and D is degradation coefficient. The fan running status and house SP were continuously monitored every 1 sec by current switch sensors (CR9321; CR Magnetic, St. Louis, MO) and SP sensors (model 264; Setra, Boxborough, MA) and averaged every 30 sec (Muhlbauer et al., 2011). The 30-sec average values of SP were plugged into the fan curves for the airflow calculation. Summation of airflow from all the running fans during each monitoring cycle produced the overall house VR. The fan belts and motors of the three houses were checked weekly during the routine quality assurance/quality control check and malfunctioning fans were recorded. In addition to the direct VR measurement, CO 2 mass balance method was used to serve as a backup or check of directly measured VR (Li et al., 2004). Due to the dust accumulation and worn belts and bearings, the degradation of fan flow rates was quantified monthly with the CO 2 mass balance method and ventilation curves were corrected for the emission rate (ER) determination. D ¼ VR Indirect VR Direct (2) where D is degradation coefficient; VR Indirect is house ventilation rate based on CO 2 mass balance method, m 3 /hr/house; and VR Direct is directly measured ventilation rate based on initial fan curve, m 3 /hr/house. SE Control DDGS EcoCal Control DDGS EcoCal ME, MJ/kg 13.7 b 13.5 a 13.6 ab CP, % * Row means followed by different superscript letters are significantly different (p < 0.05). The manure storage of each house was cleaned in November 2007 prior to the study. After 1 yr of accumulation, the manure was removed and weighed separately for each house during two periods of November 2008 to January 2009 and April There were 1.5 and 2.5 months of manure accumulation from the previous treatment for the second flock of DDGS and EcoCal diets, respectively. The houses were continuously ventilated for 3 weeks to minimize the carryover effect of aged manure before the new flocks. Manure was allowed to accumulate for least 4 weeks after the dietary reassignments to the houses before the emissions data were used in the comparison of the dietary effects. During the first manure removal (November 2008), nine manure samples from each house were collected from nine selected representative locations and analyzed for nutrient, ph, and moisture content (MC) by a (both state and federally) certified commercial laboratory (Midwest Lab, Omaha, NE). Manure MC was determined by drying the samples in an electric oven at 135 C for 2 hr (AOAC International, 1990a). Total Kjeldahl nitrogen (TKN) was measured using the improved Kjeldahl method (AOAC International, 1990b). Total ammonia nitrogen was measured by the cadmium reduction method, and ph was measured with electrodes (AOAC International, 1990c). Determination of emission rates (ERs) The gaseous ER was calculated as mass of the gas emitted from the layer houses per unit time, of the following form: ER ¼ Q N ½GŠ e ½GŠ i 10 6 w m T std P a (3) V m T a P std where ER is gaseous emission rate for the house, g/hen/t; Q is ventilation rate at field temperature and barometric pressure, m 3 / house/t; N is the number of hens in the barn that accounted for daily mortality; [G] i is volumetric gaseous concentration of ambient air, ppm v ;[G] e is volumetric gaseous concentration of exhaust ventilation air, ppm v ; T std is standard temperature, K; T a is absolute house temperature, C þ K; P std is standard barometric pressure, kpa; P a is atmospheric barometric pressure on the site, kpa; w m is molar weight of NH 3 (17.03 g/mole), CO 2 (44.01 g/mole), CH 4 (16.04 g/ mole), N 2 O (44.01 g/mole), or H 2 S ( g/mole); V m is molar volume of gas at standard temperature (0 C) and pressure ( kpa), or STP, m 3 /mole. Daily emissions were the summation of the dynamic emissions over the 24-hr period. The gaseous emission data were collected for 825 days from December 6, 2007, to March 9, 2010, and the first two full years of data were used in the final data analysis. Due to the disruptions caused by instrumentation malfunction, routine calibration and power outage, 26 days of emission data were missing and data from 705 days were available and used in the analysis. Molting was considered as a part of the lifecycle of the laying hens and the emissions during molting were included in the data analysis for the three diets. Statistical analysis was performed using SAS (SAS Institute, Cary, NC). Data were analyzed using analysis of variance (ANOVA) and considering month as a repeated measure during the period. The dietary effect was considered significant at P value 0.05.

6 164 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Table 2. Manure properties of high-rise hen houses fed three diets of Control, DDGS (10% inclusion rate), or EcoCal (7% inclusion rate) Mean SE Control DDGS EcoCal Control DDGS EcoCal NH 3 -N, % As-is 0.76 b 0.89 b 1.21 a Dry 1.46 b 1.62 b 2.44 a Org-N, % As-is Dry TKN, % As-is Dry P 2 O 5, % As-is 3.86 a 4.36 a 2.46 a Dry 7.07 a 7.70 a 4.94 b K 2 O, % As-is 2.99 a 3.02 a 1.95 b Dry 5.49 a 5.39 a 3.91 b S, % As-is 0.41 c 0.68 b 2.11 a Dry 0.74 b 1.20 b 4.24 a ph 9.3 a 8.9 b 8.0 c Moisture content, % Notes: As-is ¼ as sampled basis; Dry ¼ dry matter basis. * Row means followed by different superscript letters are significantly different (p < 0.05). Results and Discussion Effects of dietary regimens on manure nutrients and ph Manure properties for the three diets are shown in Table 2. There was no significant difference among the three diets in TKN or organic nitrogen (org-n). The manure moisture contents were 46.1%, 43.5%, and 50.2% for the Control, DDGS, and EcoCal diets, respectively. Manure of the EcoCal diet flock had higher ammonia nitrogen (NH 3 -N) and sulfur content, but lower P 2 O 5 and K 2 O than that of the Control or DDGS diet. The NH 3 - N content (2.44%, dry matter basis) of the EcoCal manure was 68% higher than that of the Control diet manure (1.46%, dry matter basis). The EcoCal diet manure contained 4.7 times higher sulfur content than the Control diet manure (4.24% vs. 0.74%, dry matter basis). Manure ph values of the three diets were 9.3, 8.9, and 8.0 for Control, DDGS, and EcoCal (P < 0.001), respectively. The relationship between ph and degradation of uric acid (the major nitrogen source in poultry manure) had been reported such that a sharp increase in ph was associated with decrease in the uric acid content of poultry manure (Burnett and Dondero, 1969). Elliot and Collins (Elliot and Collins, 1982) indicated that high ph in the stored manure would result in the majority of nitrogen loss as NH 3. DDGS, a product of fermentation, usually has high-fiber contents. Highfiber ingredients in animal diets decreased NH 3 emission because dietary fiber increases the metabolism and growth of bacterial populations in the large intestine and more N will remain in the manure as bacterial protein instead of uric acid, which is easily degraded and emitted as NH 3 (Kirchgessner et al., 1994; Roberts et al., 2007). In addition, bacterial fermentation of fiber produces short-chain fatty acids, which cause a lower manure ph (Roberts et al., 2007). Gypsum (CaSO 4 )was added to the EcoCal product as an acidifying agent, which changed the cation-anion balance of the diet. The acidifier ingredient in EcoCal reduced the manure ph and less N was emitted as aerial NH 3 into the air; consequently NH 3 -N would be more easily retained in the manure. Ventilation rate (VR) verification To utilize the CO 2 mass balance method, the CO 2 ER from manure in the storage needs to be quantified. Therefore, VR values were compared between the indirect CO 2 method and direct measurement from May 2009 to July The fan curves used for this comparison were verified before and after the comparison with 2-hr average data (Li et al., 2004). Figure 3 shows the correlation between the directly measured and Figure 3. Relationship of ventilation rate (VR) determined with direct measurement versus CO 2 balance derivation for the monitored layer house. The dashed lines below and above the regression lines represent 95% confidence intervals of the observations.

7 Li et al. / Journal of the Air & Waste Management Association 62 (2012) indirectly derived VR over the 1-week period immediately after manure cleanout from the storage. The small amounts of cumulated manure in the storage and on the manure dropping boards in the first week after manure removal accounted for 2.2% of the total CO 2 that predominantly resulted from birds respiration. The CO 2 ER from the stored manure gradually increased and stabilized at the 7th and 8th weeks after manure removal (Figure 4). Manure CO 2 emissions in the high-rise houses accounted for 2.2% to 8.8% of total CO 2 emissions (birds respiration þ manure degradation). The manure CO 2 ER (8.3% of total house CO 2 )was included in the CO 2 mass balance when manure accumulation was greater than 8 weeks. The CO 2 ER from manure in this study was similar to values reported by previous studies. Liang et al. (Liang et al., 2005) reported 5.4% to 9.0% of total CO 2 emissions in highrise houses being from manure storage. Li et al. (Li et al., 2004) concluded that the CO 2 emissions from the manure in manure-belt laying-hen houses with daily manure removal could be neglected. Ouwerkerk and Pedersen (Ouwerkerk and van Pedersen, 1994) reported that CO 2 generation by animal manure ranged from 0% to 8.5% of the total CO 2 amount, depending on the storage time and type of the manure. Greenhouse gas (GHG) emissions N 2 O emissions were below the detection limit of the measurement system, hence not included in the rest of the results presentation. Figure 5 shows the daily CO 2 ER for the three dietary regimens. Examination of the data revealed no clear trend of the dietary impact on CO 2 ER (g/hen/day), which was 63.9 to 109 for EcoCal, 62.2 to 111 for DDGS, and 61.8 to 113 for Control. The monthly CO 2 ER data for the three dietary regimens are shown in Table 3, varying from 66.0 to 97.5 g/hen/day over the 24-month monitoring period. The variation of CO 2 ER could be caused by changes in body weight, activities, and house temperature hence feed intake. The CO 2 ER from manure varied from 7.2 to 7.4 g/hen/day when 8.3% of the total CO 2 emission was from manure. There was no significant difference in CO 2 ER among the three diets (P ¼ 0.45). Since the CH 4 filter was not installed until May 2009, only 6 months of CH 4 emission data were collected during the latter part of the study (May to November, 2009) (Table 3). For the Control diet, only 4 months of data during the summer (June to September, 2009) were used due to flock change. For the Figure 4. Manure accumulation effect on the ratio of ventilation rates derived from CO 2 mass balance method versus direct measurement. Figure 5. CO 2 daily emission rates of three high-rise hen houses fed different diets.

8 166 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Table 3. Monthly mean CO 2 and CH 4 emission rates of high-rise hen houses fed three diets of Control, DDGS (10% inclusion rate), or EcoCal (7% inclusion rate) Month, Year MeanT out, C CO 2 ER, g/hen/day (SD) CH 4 ER, g/hen/day (SD) Control DDGS EcoCal Control DDGS EcoCal Dec, (1.54) 84.8 (1.68) 77.9 (1.65) Jan, (1.78) 74.8 (1.04) 77.5 (1.24) Feb, (2.10) 76.4 (0.96) 91.9 (1.81) Mar, (1.78) 78.9 (1.64) 88.9 (2.39) Apr, (1.59) 88.1 (1.35) 86.1 (1.91) May, (1.40) 89.4 (1.46) 92.6 (1.0) Jun, (1.28) 87.7 (1.18)* 92.4 (1.20) July, (1.44) 89.2 (1.40)* 93.4 (1.20) Aug, (1.14) 95.1 (0.86) 95.1 (1.17) Sep, (1.58)* 93.2 (1.26) 96.1 (1.51) Oct, (1.35)* 91.3 (1.21) 83.9 (1.84) Nov, (2.22) 93.4 (1.41) 83.1 (1.38) Dec, (1.37) 92.9 (1.46)* 88.3 (2.17) Jan, (1.24) 86.3 (1.22)* 80.4 (1.58) Feb, (1.35) 87.1 (1.88) 91.8 (1.97) Mar, (1.48) 84.8 (1.62) 94.6 (1.75) Apr, (2.15) 82.5 (3.16) 93.0 (1.59) May, (2.81) 88.9 (1.17) 92.5 (1.63) Jun, (1.88) 92.2 (1.55) 0.19 (0.02) 0.18 (0.02) July, (2.81) 79.5 (1.46) 0.20 (0.05) 0.16 (0.01) Aug, (0.73) 88.6 (1.22) 0.23 (0.03) 0.17 (0.02) Sep, (2.90) 95.6 (0.91) 82.8 (1.41) 0.18 (0.01) 0.13 (0.01) 0.12 (0.01) Oct, (1.19) 74.8 (1.28) 0.06 (0.01) 0.05 (0.01) Nov, (1.34) 75.4 (1.29) 0.05 (0.01) 0.01 (0.01) Overall Mean 9.5 (2.14) 89.6 (1.6) 87.4 (1.26) 87.3 (1.37) 0.20 (0.01) 0.12 (0.02) 0.07 (0.03) Notes: *Molting diet was used. Flock was depopulated. The new flock was considered as control before the EcoCal diet was fed. ¼ no meaningful comparison due to flock changing. EcoCal diet, only CH 4 emission from September to November 2009 were collected. The average values of CH 4 ER during the summer season (June to September) were , , and g/hen/day for the Control, DDGS, and EcoCal diets, respectively. The average CH 4 ERs were and g/hen/day, respectively, during the fall season (October and November) for DDGS and EcoCal diets. The birds with DDGS or EcoCal diet tended to emit less CH 4 than with Control diet during the summer season (P ¼ 0.04). There was a clear trend that the CH 4 ER increased with higher outside and inside temperatures and VR (P < 0.01). Higher temperature positively influences bacterial activities under anaerobic condition and thus generation of CH 4 gas. Higher VR causes lower moisture content and more porous surface area at the top of the manure pile, which enhances the volatilization of CH 4. The results of this study show the same trend on CH 4 emissions and were similar to the limited literature information. Fabbri et al. (Fabbri et al., 2007) reported CH 4 emission for deep-pit (much like the HR houses in the current study) laying-hen houses to be 0.19 g/hen/day in August 2001, but 0.01 g/hen/day during the spring season (March and April). Ammonia (NH 3 ) and hydrogen sulfide (H 2 S) emissions Daily mean NH 3 and H 2 S ER for the layer houses are shown in Figures 6 and 7. Monthly mean ( SE) NH 3 and H 2 S ER for the Control, DDGS, and EcoCal diets over the 24-month monitoring period are summarized in Table 4. The monthly mean ( SE) NH 3 ER was the lowest for the EcoCal diet ( g/hen/day), followed by the DDGS diet ( g/hen/day), and highest for the Control diet ( g/hen/day) (P < 0.01) (Table 4). Wathes et al. (Wathes et al., 1997) reported an NH 3 ER of 0.77 g/hen/day in winter and 1.16 g/hen/day in summer for four deep-pit layer houses with standard diet in England. According to Liang et al. (Liang et al., 2005), two HR houses (in Iowa) with standard diet over a 1-yr monitoring period had an ER of g/hen/day, which was similar to the NH 3 ER of Control diet in the current study. In the same study, two HR houses with 1% lower CP diet showed lower NH 3 ER of g/hen/day. Wu-Haan et al. (Wu-Haan et al., 2007) reported an average 38.9% (27.3% to 45.9%) NH 3 emission reduction for 640 laying hens housed in environment-controlled chambers over 3-week periods while the birds were fed a diet containing 6.9% of a

9 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Figure 6. NH 3 daily emission rates of three high-rise hen houses fed different diets. Figure 7. H 2 S daily emission rates of three high-rise hen houses fed different diets. CaSO 4 -zeolite mixture and slightly reduced CP. In the current study (Figure 8), the efficacy of NH 3 emission reduction by the EcoCal diet decreased with increasing outside temperature, varying from 7.1% in September 2008 to 72.2% in February In comparison, NH 3 ER reduction for the DDGS diet varied from 16.3% in September 2008 to 51.0% in October The results thus demonstrate that the efficacy of NH 3 emission reduction by the DDGS or EcoCal diet was seasondependent (P < 0.01). The overall NH 3 emission reduction rates for the 2-yr period were 14.3% and 39.2% for the DDGS and EcoCal regimens, respectively. The outcome of the seasonally variable dietary efficacy could have stemmed from changes in manure properties, especially moisture content and ph, as the weather and VR varied considerably with the season. The monthly mean H 2 S ER for the EcoCal diet ( mg/hen/day) was significantly higher than that of the DDGS ( mg/hen/day) or Control diet ( mg/ hen/day) (P < 0.001). However, no difference in H 2 SERwas observed between DDGS and Control (P ¼ 0.23). Monthly mean H 2 S ER increase varied from 1.4% to 499% for the EcoCal diet. The overall H 2 S ER increased 6.7% and 202% for the DDGS and EcoCal diets, respectively. The elevated H 2 S emission from the EcoCal diet presumably resulted from the higher content of sulfur compound, gypsum (CaSO 4 ), in the diet. An increasing H 2 S emission (4.08 vs mg/hen) from laying hens had also been shown by Wu-Haan et al. (Wu-Haan et al., 2007) when a diet with 6.9% CaSO 4 -zeolite was compared to a standard commercial diet. It should be noted that the absolute

10 168 Li et al. / Journal of the Air & Waste Management Association 62 (2012) Table 4. Monthly mean NH 3 and H 2 S emission rates of high-rise hen houses fed three diets of Control, DDGS (10% inclusion rate), or EcoCal (7% inclusion rate) Month, Year MeanT out, C NH 3 ER, g/hen/day (SD) H 2 S ER, mg/hen/day (SD) Control DDGS EcoCal Control DDGS EcoCal Dec, (0.04) 0.60 (0.05) 0.48 (0.04) 1.66 (0.06) 1.46 (0.13) 2.23 (0.14) Jan, (0.06) 0.92 (0.03) 0.40 (0.02) 2.43 (0.14) 1.89 (0.11) 4.25 (0.14) Feb, (0.04) 0.72 (0.02) 0.35 (0.01) 2.03 (0.10) 1.80 (0.04) 6.99 (0.33) Mar, (0.05) 0.76 (0.04) 0.39 (0.02) 2.4 (0.09) 1.81 (0.07) 8.97 (0.28) Apr, (0.04) 1.19 (0.07) 0.62 (0.02) 2.89 (0.07) 1.99 (0.07) 7.59 (0.21) May, (0.05) 1.05 (0.05) 0.71 (0.04) 2.39 (0.08) 1.90 (0.09) 5.80 (0.04) Jun, (0.07) 1.07 (0.05) 0.92 (0.04)* 3.17 (0.11) 2.12 (0.15) 7.36 (0.59)* July, (0.07) 1.18 (0.04) 0.90 (0.05)* 2.97 (0.13) 3.68 (0.24) 2.04 (0.11)* Aug, (0.04) 1.16 (0.04) 1.06 (0.03) 2.27 (0.10) 3.44 (0.19) 2.24 (0.17) Sep, (0.06)* 1.09 (0.05) 1.00 (0.04) 1.45 (0.18)* 2.52 (0.13) 5.93 (0.32) Oct, (0.04)* 0.85 (0.04) 0.69 (0.04) 0.76 (0.06)* 1.46 (0.05) 4.46 (0.24) Nov, (0.04) 0.66 (0.05) 0.58 (0.03) 0.85 (0.10) 1.50 (0.18) 4.11 (0.45) Dec, (0.02) 0.73 (0.04)* 0.58 (0.04) 1.05 (0.11) 1.95 (0.23)* 3.98 (0.44) Jan, (0.05) 0.80 (0.06)* 0.36 (0.01) 1.78 (0.13) 0.97 (0.13)* 6.33 (0.37) Feb, (0.04) 0.96 (0.03) 0.22 (0.01) 1.38 (0.05) 1.17 (0.05) 7.45 (0.29) Mar, (0.03) 0.80 (0.02) 0.26 (0.01) 0.93 (0.04) 1.34 (0.06) 7.10 (0.46) Apr, (0.04) 0.60 (0.04) 0.46 (0.02) 1.06 (0.05) 1.70 (0.09) 5.39 (0.20) May, (0.03) 0.76 (0.02) 0.68 (0.06) 0.80 (0.08) 1.57 (0.08) 4.79 (0.20) Jun, (0.06) 0.94 (0.06) 1.35 (0.10) 1.71 (0.21) July, (0.14) 0.61 (0.03) 1.85 (0.47) 1.59 (0.07) Aug, (0.03) 0.72 (0.03) 2.03 (0.10) 2.47 (0.11) Sep, (0.08) 0.58 (0.02) 0.67 (0.05) 1.94 (0.09) 2.06 (0.05) 2.30 (0.09) Oct, (0.02) 0.47 (0.02) 1.31 (0.08) 2.59 (0.26) Nov, (0.02) 0.40 (0.01) 1.48 (0.07) 3.57 (0.01) Overall mean 9.5 (2.14) 0.96 (0.05) 0.82 (0.05) 0.58 (0.05) 1.79 (0.16) 1.99 (0.13) 5.39 (0.46) Notes: *Molting diet was used. Flock was depopulated. The new flock was considered as control before the EcoCal diet was fed. ¼ no meaningful comparison due to flock changing. Figure 8. Monthly NH 3 reduction rate by the EcoCal or DDGS diet and outside temperature. values of the H 2 S ER for all the dietary regimens were much lower than those of NH 3 ER. The overall mean H 2 S concentrations in the manure storage level were 0.045, 0.048, and 0.13 ppm v during the 2-yr period for Control, DDGS, and EcoCal diets, respectively. Hence, the trade-off of significantly reducing NH 3 emission while keeping the H 2 S emission at low levels (though elevated in relative terms) is justifiable. Summary and Conclusions A 2-yr field study was conducted that aimed to verify the impactoffeedinganecocaldietat7%inclusionrateora DDGS diet at 10% inclusion rate, as compared to the standard industry (Control) diet, to laying hens in high-rise houses in Iowa, USA, on gaseous emissions and manure

11 Li et al. / Journal of the Air & Waste Management Association 62 (2012) properties. The following conclusions and observations were made. The EcoCal and DDGS diets led to an overall NH 3 emissions reduction of 39.2% and 14.3%, respectively, relative to the Control diet. The NH 3 emission rates (mean SE) were , , and g/hen/day for the EcoCal, DDGS, and Control diet, respectively. The EcoCal and DDGS diets led to an overall H 2 S emissions increase of 202% and 7%, respectively. The H 2 S emission rates (mean SE) were , and mg/hen/day for the EcoCal, DDGS, and Control diet, respectively. The efficacy of NH 3 emission reduction by the EcoCal diet decreased with increasing outside temperature, varying from 7.1% in September 2008 (mild weather) to 72.2% in February 2009 (cold weather). The birds with DDGS and EcoCal diets tended to emit less CH 4 than with Control diet during the monitored summer season. There was no difference in CO 2 emissions among the three dietary regimens, averaging 87.3 ( 1.37), 87.4 ( 1.26), and 89.6 ( 1.6) g/hen/day for EcoCal, DDGS, and Control, respectively. The manure of EcoCal diet contained 68% higher NH 3 -N and 4.7 times higher sulfur content than the Control diet manure (1.46% on dry matter basis). Manure ph values of the three diets were 8.0, 8.9, and 9.3 for EcoCal, DDGS, and Control, respectively. Acknowledgments Financial support of the study was provided in part by the USDA NRCS Conservation Innovation Grant Program (Award NRCS 69-3A ), American Egg Board, United Egg Association, Rose Acre Farms, National Corn Growers Association, and Iowa State University. The authors wish to express their sincere appreciation to Rose Acre Farm staff for their close cooperation throughout the study. References AOAC International. 1990a. AOAC Official Method Official Methods of Analysis of AOAC International. Gaithersburg, MD: AOAC International. AOAC International. 1990b. AOAC Official Method Official Methods of Analysis of AOAC International. Gaithersburg, MD: AOAC International. AOAC International. 1990c. AOAC Official Method Official Methods of Analysis of AOAC International. Gaithersburg, MD: AOAC International. Burnett, W.E., and N.C. Dondero, Microbiological and chemical changes in poultry manure associated with decomposition and odor generation. In Animal Waste Management. Proceedings of Cornell University Conference of Agriculture Waste Management, Ithaca, NY, January Ithaca, NY: Cornell University. pp Elliot, H.A., and N.E. Collins Factors affecting ammonia release in broiler houses. Trans. ASAE. 25: Fabbri, C., L. Valli, M. Guarino, A. Costa, and V. Mazzotta Ammonia, methane, nitrous oxide and particulate matter emissions from two different buildings for laying hens. Biosys. Eng. 97: Kirchgessner, M., M. Kreuzer, A. Machmüller, and D.A. Roth-Maier Evidence for a high efficiency of bacterial protein synthesis in the digestive tract of adult sows fed supplements of fibrous feedstuffs. Anim. Feed Sci. Technol. 46: Li, H., and H. Xin Lab-scale assessment of gaseous emissions from layinghen manure storage as affected by physical and environmental factors. Trans. ASABE 53: Li, H., H. Xin, Y. Liang, R.S. Gates, E.F. Wheeler, and A. Heber Comparison of direct vs. indirect ventilation rate determination for manurebelt laying hen houses. Trans. ASAE. 48: Liang, Y., H. Xin, E.F. Wheeler, R.S. Gates, H. Li, J.S. Zajaczkowski, P.A. Topper, K.D. Casey, B.R. Behrends, D.J. Burnham, and F.J. Zajaczkowski Ammonia emissions from U.S. laying hen houses in Iowa and Pennsylvania. Trans. ASAE. 48: Muhlbauer, R.V., T.A. Shepherd, H. Li, R.T. Burns, and H. Xin Technical note: Development and application of an induction-operated current switch for monitoring fan operation. Appl. Eng. Agric. 27: Ouwerkerk, E.N.J., and S. van Pedersen, Application of the carbon dioxide mass balance method to evaluate ventilation rates in livestock buildings. In Proceedings of the 12th CIGR World Congress on Agricultural Engineering, Milan, Italy, August 29 September 1. Merelbeke, Belgium: CIGR. Vol. 1, pp Roberts, S.A., H. Xin, B.J. Kerr, J.R. Russell, and K. Bregendahl Effects of dietary fiber and reduced crude protein on ammonia emission from layinghen manure. Poult. Sci. 86: Sutton, A.L., T. Applegate, S. Hankins, B. Hill, G. Allee, W. Greene, R. Kohn, D. Meyer, W. Powers, and T. van Kempen, Manipulation of Animal Diets to Affect Manure Production, Composition and Odors: State of the Science. White Paper. National Center for Manure and Animal Waste Management: Raleigh, NC. U.S. Environmental Protection Agency, National Emission Inventory Ammonia emissions from animal husbandry operations. ttnchie1/ap42/ch09/related/nh3inventorydraft_jan2004.pdf (accessed March, 2005). United Egg Producers, Animal Husbandry Guidelines for U.S. Egg Laying Flocks edition. Welfare-Guidelines.pdf Wathes, C.M., M.R. Holden, R.W. Sneath, R.P. White, and V.R. Phillips Concentrations and emission rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust, and endotoxin in U.K. broiler and layer houses. Br. Poult. Sci. 38: Wu-Haan, W., W.J. Powers, C.R. Angel, C.E. Hale, III, and T.J. Applegate Effect of an acidifying diet combined with zeolite and slight protein reduction on air emissions from laying hens of different ages. Poult. Sci. 86: About the Authors Hong Li is an assistant professor in the Department of Animal and Food Sciences and Department of Bioresources Engineering at University of Delaware, Newark, DE. Hongwei Xin is a professor in the Department of Agricultural and Biosystems Engineering at Iowa State University, Ames, IA. James Kliebenstein is a professor in the Department of Economics at Iowa State University, Ames, IA. Robert I. Burns is a professor and Assistant Dean for Agriculture, Natural Resources & Resource Development at the University of Tennessee, Knoxville, TN. Stacey A. Roberts is a poultry nutritionist at Akey Nutrition and Research Center, Lewisburg, OH. Shuhai Li is a research scientist at Renewable Energy Training Center, SUNY Morrisville, NY. Kristjan Bregendahl is a poultry nutritionist at Sparboe Farms, Litchfield, MN.