Source: PENNSYLVANIA STATE UNIVERSITY submitted to NRP
POULTRY PRODUCTION SYSTEMS: OPTIMIZATION OF PRODUCTION AND WELFARE USING PHYSIOLOGICAL, BEHAVIORAL, AND PHYSICAL ASSESSMENTS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0202866
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
NE-1022
Project Start Date
Oct 1, 2004
Project End Date
Jun 30, 2009
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK,PA 16802
Performing Department
AGRICULTURAL & BIOLOGICAL ENGINEERING
Non Technical Summary
The poultry industry is increasingly challenged to address consumer and general public concerns about animal welfare and environmental issues. Project information on housing environments can be used to define environmental conditions - aerial, thermal, spectral, spatial, and nutritional - and management practices that will result in production systems that promote bird welfare and performance.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3063299202050%
4013299202050%
Knowledge Area
401 - Structures, Facilities, and General Purpose Farm Supplies; 306 - Environmental Stress in Animals;

Subject Of Investigation
3299 - Poultry, general/other;

Field Of Science
2020 - Engineering;
Goals / Objectives
Characterize physiological, behavioral and performance responses of poultry to their physical and social environments and to various management practices, with the ultimate goal of enhancing animal welfare and ensuring environmental soundness while maintaining viable production profitability.
Project Methods
This is a multi-state project so approach varies depending on collaborative work of the sub projects. The critical questions proposed as the focus of this project are as follows: 1) What physiological and behavioral parameters are disrupted by stress episodes of various types and durations, and how are they disrupted mechanistically? 2) Can the disruptions be prevented or reversed by environmental manipulations? 3) What management technologies are suggested by answering Questions 1 and 2?

Progress 10/01/04 to 06/30/09

Outputs
OUTPUTS: A USDA IFAFS-funded research project on-farm data collection was completed, data analyzed and published. Project scope included field evaluation of 8 commercial poultry houses in PA (along with 12 other houses in KY and IA) with some houses demonstrating emission-reduction strategies. Ammonia level was determined using an electrochemical sensor system developed by the project investigators. Ventilation rate was estimated by monitoring building static pressure difference and runtime of the ventilation fans whose airflow rates were determined in situ with a portable anemometer array. Similar emissions were seen from similar poultry housing situations across the states. More frequent manure removal resulted in lower house emissions (manure storage emissions would be impacted). Four turkey houses were also monitored utilizing instrumentation from the above project to gather and publish findings. Another completed project assessed ammonia mitigation strategies from layer hen houses using balanced diets modified with pH-reducing and ammonia-binding agents (in cooperation with Iowa State University, ISU). A second layer hen project, in collaboration with ISU, University of Illinois, and United Egg Producers, is demonstrating to egg producers nationwide that the feeding of the ethanol by-product, dried distillers grains with solubles (DDGS), as part of a properly balanced diet can result in dramatic reduction in ammonia emissions while maintaining production performance. The Penn State Odor Assessment Laboratory has partnered with a variety of funded research sources from industry (AgraKey), federal-granting agency (USDA), municipal government (City of Philadelphia), consulting firm (Material Matters), and another University (Bucknell). The lab features a qualified panel of odor assessors using a forced-choice dynamic olfactometer operated under international standard protocols. The lab conducted poultry odor evaluations of shelterbelt effectiveness currently under review for publication. A final project is developing a national curriculum on agricultural air quality that addresses livestock and poultry issues of interest throughout the U.S. in collaboration with faculty from other universities, led by University of Nebraska. PARTICIPANTS: A. Adrizal, Post-Doc, Poultry Science [PS], experimental design and conduct of dietary trials; Arlene Adviento-Borbe, Post-Doc, Agricultural and Biological Engineering [ABE], statistical analysis, research design, and instrumentation quality-assurance quality-control [QAQC]; Robin C. Brandt: Lecturer, ABE, Director Penn State Odor Assessment Lab, oversee lab and field odor emission collections and human odor-panel QAQC; Heather Burley, MS student PS, data analysis; Hershel Elliott, Professor, ABE, design and analysis of bio-geo-chemical aspects of experimental trials; Richard Gates, Professor, ABE University of Illinois, technical director, instrumentation; Chad Gregory, Vice President, United Egg Producers, project management, outreach; Paul Patterson, Professor, PS, oversight of poultry nutrient management aspects of projects and oversee PS post-doc and graduate students, outreach; Ahmet Pekel, MS student, PS, data collection and interpretation; Richard Stowell, Associate Professor, Biological Systems Engineering, University of Nebraska, outreach through eXtension, curriculum development; Deborah Topper, Technologist, ABE, operator and QAQC of dynamic olfactometer during panel assessment; Patrick Topper, Senior Research Technologist, ABE, design, fabrication, and operation of lab and field, odor and gas emission collections; Eileen Wheeler, Professor, ABE, primary administrative manager and technical director to oversee implementation, QAQC, and analysis of all trials, supervise technologists and ABE post-doc, outreach; Hongwei Xin, Professor, Agricultural and Biosystems Engineering, Iowa State University, technical and analytical collaborator, outreach. TARGET AUDIENCES: Poultry producers are targeted for environment-related information including emission reduction recommendations. Advisors to producers (servicemen, veterinarians, Extension educators, etc.) benefit from nutrient options for diet formulation and understanding of principles behind the recommendations for environmental improvements related to nutrient management. Air quality researchers in other PSU departments and at other universities use the instrumentation systems developed during these multi-discipline, multi-state projects for their own air quality projects. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
This multi-state, multi-disciplinary effort has developed and published the most comprehensive database of baseline ammonia emissions available at this time for broiler chicken and laying hen facilities. Emissions from several types of poultry houses can be estimated for comparison among emissions abatement strategies. The published work presents effective strategy for on-farm data collection with accurate data obtained in rugged poultry housing environments. Instrumentation developments to accurately and affordably monitor gas emissions from poultry housing have been a primary impact. Other universities and research projects within the host institutions have adopted these instrumentation systems in air quality studies. Data from the poultry ammonia emissions evaluations continue to document management strategies that can improve air quality within and around poultry facilities. Curriculum development is creating air quality learning modules directed at senior undergraduate level education and Extension programs for professionals who are advising farmers. Olfactometry capabilities of the Penn State Odor Assessment Laboratory have expanded in scope with the addition of validated field olfactometry and qualifications of odor (intensity, pleasantness, description) along with dynamic olfactometry work. Nutrient management of laying hens is focused on bird health, productivity and surrounding aerial environment while utilizing reduced-cost diets.

Publications

  • Gay, S. W., E. F. Wheeler, J. L. Zajaczkowski, and P. A. Topper. 2006. Ammonia emissions from U.S. tom turkey grow out and brooder houses under cold weather mechanical ventilation. Applied Engineering in Agriculture 22(1):127-134.
  • Casey, K. D., R. S. Gates, A. Singh, A. J. Pescatore, E. F. Wheeler, H. Xin, and Y. Liang. 2006. Managing litter to reduce ammonia emissions from broiler chicken houses in the U.S.A. In Proceedings of Poultry Information Exchange 2006. Gold Coast, Australia.: PIX Association Inc. pp. 181-189.
  • Cimbala, J. M., S. R. Pawar, D. V. Lindberg, and E. F. Wheeler. 2006. CFD Calculations Modeling the Spread of Airborne Diseases in Poultry Houses. Final Report to Penn State Indoor Environment Center. The Pennsylvania State University, University Park, PA. 4 pp.
  • Brandt, R. C., H. A. Elliott, E. F. Wheeler, P. H. Heinemann, J. Zhu, and D. Shuman. 2007. Field olfactometry for quantifying and targeting agricultural odor control. Final Report. Pa Dept. of Agriculture. Harrisburg, PA. 101 pp.
  • Adrizal, A., P. H. Patterson, R. M. Hulet, R. M. Bates, D. A. Despot, E. F. Wheeler, P. A. Topper, D. A. Anderson, and J. R. Thompson. 2008. The potential for plants to trap emissions from farms with laying hens: 2. Ammonia and Dust. Journal of Applied Poultry Research 17:398-411.
  • Patterson, P. H., T. L. Cravener, E. F. Wheeler, and P.A. Topper. 2008. Dietary acids for laying hens: performance and egg and environmental parameters. Poultry Science 87. Supplement 1:63.
  • Wheeler, E. F. 2009. Air Quality-Impact and Regulatory Issues. Ag a la Carte, Lunchtime Webinar Series Presents: Manure Du Jour. Penn State College of Ag Sciences, University Park, PA. 1 pp. http://aec.cas.psu.edu/news/manurewebinar.asp
  • Wheeler, E. F., S. Shortle, R. Brandt, R. Meinen, and K. S. Blunke. 2009. Air Quality and Animal Agriculture: The Basics. Ag a la Carte, Manure Du Jour fact sheet. Penn State College of Ag Sciences, University Park, PA. 2 pp.
  • Topper, P. A. and E. F. Wheeler. 2005. Evaluation of Five Chicken Drinker Designs for Water Flow Rate During Finger Flow and Simulated Bird Flow. Final Report for Chore Time Corporation. The Pennsylvania State University, Agricultural and Biological Engineering, University Park, PA. 41 pp.
  • Gates, R. S., H. Xin, and E. F. Wheeler. 2005. Reducing Ammonia Emissions from Poultry Houses by Enhanced Manure and Diet Management. Final Report for US Department of Agriculture, Initiative for Future Agriculture and Food Systems (IFAFS), Washington, DC. (bibliography of project publications) 7 pp.


Progress 10/01/07 to 09/30/08

Outputs
OUTPUTS: The three primary focuses of poultry research and outreach efforts are: 1. odor and gas baseline emission monitoring; 2. instrumentation development for accurate emission determination; and 3. evaluation of gas mitigation strategies. One completed project assessed ammonia mitigation strategies from layer hen houses using balanced diets modified with pH-reducing and ammonia-binding agents (in cooperation with Iowa State University, ISU). A second layer hen project, in collaboration with ISU, University of Kentucky, and United Egg Producers, is demonstrating to egg producers nationwide that the feeding of the ethanol by-product, dried distillers grains (DDGS), as part of a properly balanced diet can result in dramatic reduction in ammonia emissions while maintaining production performance. Instrumentation from additional projects (investigating dairy gas emissions) is being evaluated for use in naturally-ventilated facilities' gas emissions and for comparison among strategies to reduce emissions. The Penn State Odor Assessment Laboratory has completed its first year of operation in partnership with a variety of funded research sources from industry (AgraKey), federal-granting agency (USDA), municipal government (City of Philadelphia), consulting firm (Material Matters), and another University (Bucknell). The lab features a qualified panel of odor assessors using a forced-choice dynamic olfactometer operated under international standard protocols. The lab has recently been used in poultry odor evaluations of shelterbelt effectiveness. A final project is developing a national curriculum on agricultural air quality that addresses livestock and poultry issues of interest throughout the U.S. in collaboration with faculty from other universities, led by University of Nebraska. PARTICIPANTS: All participants facilitate publications, presentations, and Extension education in their specialty area, in addition to the following specific tasks: Adrizal, Post-Doc, PS, experimental design and conduct of dietary trials. Arlene Adviento-Borbe, Post-Doc, ABE, statistical analysis, research design, and instrumentation QAQC; Robin C. Brandt: Lecturer, ABE, oversee establishment and supervise operation of the Odor Lab, oversee lab and field odor emission collections and human odor-panel QAQC; Hershel Elliott, Professor, ABE, design and analysis of bio-geo-chemical aspects of experimental trials ; Paul Patterson, Professor, PS, oversight of poultry nutrient management aspects of projects and oversee PS post-doc; Deborah Topper, Technologist, ABE, operator and QAQC of dynamic olfactometer during panel assessment; Patrick Topper, Senior Research Technologist, ABE, design, fabrication, and operation of lab and field, odor and gas emission collections; Eileen Wheeler, Professor, ABE, primary administrative manager and technical director to oversee implementation, QAQC, and analysis of all trials, supervise technologists and ABE post-doc.(Department abbreviations: ABE=ag & biological engineering; PS=poultry science) TARGET AUDIENCES: Poultry producers are targeted for emissions-related information including emission reduction recommendations. Advisors to producers (servicemen, veterinarians, Extension educators, etc.) benefit from emissions baseline data and understanding of principles behind the recommendations for mitigation. Air quality researchers in other PSU departments and at other universities use the instrumentation systems developed during these multi-discipline, multi-state projects for their own air quality projects PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Curriculum development is creating air quality learning modules directed at senior undergraduate level education and Extension programs for professionals who are advising farmers. Olfactometry capabilities of the Penn State Odor Assessment Laboratory have expanded in scope during the first year of operation with the addition of validated field olfactometry and qualifications of odor (intensity, pleasantness, description) in addition to the already established dynamic olfactometry work. Nutrient management of laying hens is focused on bird health, productivity and surrounding aerial environment while utilizing reduced-cost diets. Instrumentation developments to accurately and affordability monitor gas emissions from poultry housing have been a primary impact of recent studies. Other universities and research projects within Penn State have adopted these instrumentation systems in air quality studies.

Publications

  • Adrizal, P. H. Patterson, R. M. Hulet, R. M. Bates, D. A. Despot, E. F. Wheeler, P. A. Topper, D. A. Anderson, and J. R. Thompson. 2008. The potential for plants to trap emissions from farms with laying hens: 2. Ammonia and Dust. Journal of Applied Poultry Research. 17:398-411.
  • Topper, P. A., E. F. Wheeler, J. S. Zajaczkowski, R. S. Gates, H. Xin, Y. Liang, and K. D. Casey. 2008. Ammonia emissions from two empty broiler houses with built-up litter. Transactions of the ASABE. 51 (1): 219-225.
  • Green, A. R., R. S. Gates, L. M. Lawrence, and E. F. Wheeler. 2008. Continuous recording reliability analysis of three monitoring systems for house core body temperature. Computers and Electronics in Agriculture. 61: 88-95.
  • Patterson, P. H., Adrizal, R. M. Hulet, R. M. Bates, D. A. Despot, E. F. Wheeler, and P. A. Topper. 2008. The potential for plants to trap emissions from farms with laying hens: 1. Ammonia. Journal of Applied Poultry Research. 17:54-63.
  • Casey, K. D., R. S. Gates, E. F. Wheeler, H. Xin, Y. Liang, A. J. Pescatore, and M. J. Ford. 2008. On-farm fan performance: Implications for ventilation and operating cost. Journal of Applied Poultry Research. 17(2): 283-295.
  • Wheeler, E. F., K. D. Casey, R. S. Gates, and H. Xin. 2008. Ammonia emissions from USA broiler barns managed with new, built-up, or acid-treated litter. Proceedings of the Eighth International Livestock Environment Symposium. Iguassu Falls City, Brazil. ASABE. St. Joseph, MI. 7 pp.
  • Wheeler, E. F., K. Casey, R. Gates, H. Xin, Y. Liang, and P. Topper. 2008. Ammonia emissions from commercial broiler chicken houses under three litter management strategies. Proceedings of the Mitigation of Air Emissions from Animal Feeding Operations. Iowa State University, Ames, IA. 5 pp.
  • Liang, Y., H. Xin, H. Li, R. S. Gates, E. F. Wheeler, and K. D. Casey. 2008. Dietary manipulation to reduce ammonia emission from high-rise layer houses. Mitigation of Air Emission from Animal feeding Operations. Iowa State University, Ames, IA. 5 pp.


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Odor and gas baseline emission monitoring, instrumentation development for accurate emission determination, and evaluation of gas mitigation strategies are the three primary focuses of poultry research and outreach efforts. One new funded project is assessing ammonia mitigation strategies from layer hen houses using balanced diets modified with pH-reducing and ammonia-binding agents (in cooperation with Iowa State University, ISU). Upcoming work will evaluate scrubbing/filtering ammonia from hen house exhaust. A second project, in collaboration with ISU, University of Kentucky, and United Egg Producers, is designed to demonstrate to egg producers nationwide that the feeding of the ethanol by-product, dried distillers grains (DDGS), as part of a properly balanced diet can result in dramatic reduction in ammonia emissions while maintaining production performance. Instrumentation from additional projects (investigating dairy gas emissions) is being developed for evaluation of naturally-ventilated facilities' gas emissions and for comparison among strategies to reduce emissions. An odor assessment laboratory, featuring a forced-choice dynamic olfactometer and field olfactometers, has been developed and is available for use in poultry odor evaluations (currently used in municipal bio-solids and dairy manure odor assessments). Additional collaboration is developing a national curriculum on agricultural air quality that addresses livestock and poultry issues of interest throughout the U.S. PARTICIPANTS: Patrick Topper, Deborah Topper, Arlene Adviento-Borbe, Paul Patterson, and Adrizal TARGET AUDIENCES: Poultry producers are targeted for emissions-related information including emission reduction recommendations. Advisors to producers (servicemen, veterinarians, Extension educators, etc.) benefit from emissions baseline data and understanding of principles behind the recommendations for mitigation. Air quality researchers in other PSU departments and at other universities use the instrumentation systems developed during these multi-discipline, multi-state projects for their own air quality projects.

Impacts
Instrumentation developments to accurately and affordably monitor gas emissions from poultry housing have been a primary impact of recent studies. Other universities and research projects within Penn State have adopted these instrumentation systems in air quality studies. Data from the poultry ammonia emissions evaluations continue to document management strategies that can improve air quality within and around poultry facilities.

Publications

  • Pawar, S. R., J. M. Cimbala, E. F. Wheeler, and D. V. Lindberg. 2007. Analysis of poultry house ventilation using computation fluid dynamics. Transactions of the ASABE 50(4):1373-1382.
  • Wheeler, E. F., P. A. Topper, N. E. Brown, and G. A. Varga. 2007. Multiple-Chamber Steady-State Gas Emission Detection from Dairy Manure Slurry. CD-ROM Proceedings of International Symposium on Air Quality and Waste Management for Agriculture. St. Joseph, MI. ASABE Publication Number 701P0907. CD ROM
  • Wheeler, E. F., P. A. Topper, and T. L. Richard. 2007. Validation of Flux Chamber Technique for Estimating Gas Emission in Situ from Naturally-Ventilated Facilities. CD-ROM Proceedings of International Symposium on Air Quality and Waste Management for Agriculture. St. Joseph, MI. ASABE Publication Number 701P0907. CD ROM
  • Wheeler, E. F., R. S. Gates, H. Xin, K. Casey, P. Topper, and Y. Liang. 2007. Ammonia emissions from laying hen and broiler houses in the U.S.A. In Proceedings Ammonia Emissions in Agriculture, eds. G-J Monteny and E. Hartung. Wageningen Academic Publishers. pp. 178-179.
  • Casey, K. D., R. S. Gates, E. F. Wheeler, H. Xin, and Y. Liang. 2007. Quantifying measurement uncertainty for the multi-state broiler ammonia emissions project. In Proceedings Ammonia Emissions in Agriculture, eds. G-J Monteny and E. Hartung. Wageningen Academic Publishers. pp. 343-344.
  • Gates, R. S., K. D. Casey, E. F. Wheeler, H. Xin, and A. J. Pescatore. 2007. U.S. broiler housing ammonia emissions inventory. Atmospheric Environment. (In Press)


Progress 01/01/06 to 12/31/06

Outputs
Publications continue to be produced from the advances in instrumentation and the comprehensive data contained in a completed multi-state USDA IFAFS-funded project. Four turkey houses were also monitored utilizing instrumentation from the above project to gather some published data in those environments. Twelve commercial broiler houses and ten commercial layer hen houses in the U.S. were monitored over the course of one year to obtain ammonia emission data. Additional funded research projects continue the gas emissions inventory and instrumentation developments. Although investigating dairy cattle housing, the instrumentation methods for naturally ventilated facilities are currently being and will be applied to poultry environments.

Impacts
Instrumentation developments to accurately and affordably monitor gas emissions from poultry housing have been a primary impact of these studies. Other universities and research projects within the host institutions have adopted these instrumentation systems in air quality studies. Data from the poultry ammonia emissions evaluations continue to document management strategies that can improve air quality within and around poultry facilities.

Publications

  • Wheeler, E. F., Casey, K. D., Gates, R. S., Xin, H., Zajaczkowski, J. L., Topper, P. A., Liang, Y. and Pescatore, A. J. 2006. Ammonia emissions from twelve USA broiler chicken houses. Transactions of ASABE 49(5):1495-1512.
  • Wheeler, E. F., Topper, P. A., Varga, Y.G.A., Brown, N., Graves, R. E., Ishler, V., Heinrichs, A. J., and Vidal, V. B. 2006. Ammonia emission monitoring using flux chamber methods. In Proceedings World Congress: Agricultural Engineering for a Better World. Bonn, Germany. Abstract pp 439-440; Full paper 8 pp on CD.
  • Gates, R. S., Casey, K. D., Wheeler, E. F. and Xin, H. 2006. Estimating annual NH3 emissions from US broiler facilities. In Proceedings Agricultural Air Quality Workshop, Washington DC. pp. 205-207.
  • Casey, K. D., Gates, R. S., Pescatore, A. J., Xin, H., Liang, Y. and Wheeler, E. F. 2006. Comparison of measured estimates of annual ammonia emissions from poultry production facilities with mass balance modeling approach. In Proceedings Agricultural Air Quality Workshop, Washington DC. pp. 542-545.
  • Blanes, V., Topper, P. and Wheeler, E. F. 2006. Development and validation of a static flux chamber for measuring ammonia emission from dairy cow manure. In Proceedings World Congress: Agricultural Engineering for a Better World. Bonn, Germany. Abstract pp 431-432; Full paper 8 pp on CD.


Progress 01/01/05 to 12/31/05

Outputs
A USDA IFAFS-funded research project on-farm data collection was completed and data analysis is in final phases. Project scope included field evaluation of 8 commercial poultry houses in PA (along with 12 other houses in KY and IA) with some houses demonstrating emission-reduction strategies. Ammonia level was determined using an electrochemical sensor system developed by the project investigators. Ventilation rate was estimated by monitoring building static pressure difference and runtime of the ventilation fans whose airflow rates were determined in situ with a portable anemometer array. Similar emissions were seen from similar poultry housing situations across the states. More frequent manure removal resulted in lower house emissions (manure storage emissions would be impacted). Project website contains more information: www.bae.uky.edu/IFAFS

Impacts
The project has resulted in the most comprehensive ammonia emissions baseline data available at this time in the USA for broiler chicken and laying hen facilities. Emissions from several types of poultry houses can be used on-farm for comparison among emissions abatement strategies. The published work presents effective strategy for on-farm data collection with accurate data obtained in rugged poultry/livestock housing environments. This multi-state, multi-disciplinary project has developed and published a comprehensive database of ammonia emissions. Three peer-reviewed journal articles are in print, with another four in-press.

Publications

  • Liang, Y., Xin, H., Wheeler, E. F., Gates, R. S., Li, H., Zajaczkowski, J. S., Topper, P. A., Casey, K.D., Behrends, B. R., Burnham, D. J., and Zajaczkowski, F. J . 2005. Ammonia emissions from U.S. laying houses in Iowa and Pennsylvania. Transactions of the ASAE. 48(5):1927-1941.
  • Gates, R. S., Xin, H., Liang, Y., Casey, K. D., and Wheeler, E. F. 2005. Method for measuring ammonia emissions from poultry houses. J. Appl. Poult. Res. 14:622-634.
  • Li, H., Xin, H., Liang, Y., Gates, R. S., Wheeler, E. F., and Heber, A. J. 2005. Comparison of direct vs. indirect ventilation rate determination rates in layer barns using manure belts. Transactions of the ASAE, 48(1):367-372.
  • Gates, R. S., Casey, K. D., Pescatore, A. J., Wheeler, E. F., and Xin, H. 2005. Assessing annual U.S. broiler house emissions. Paper #1292, Air and Waste Management Association 98th Annual Conference, Minneapolis, MN. June 21-24. AWMA. 8 pp.
  • Casey, K. D., Gates, R. S., Singh, A., Pescatore, A. J., Wheeler, E. F., Xin, H., and Liang, Y. 2005. The effect of litter management on ammonia emissions from U.S. broiler chicken houses. Paper #615, Air and Waste Management Association 98th Annual Conference, Minneapolis, MN. June 21-24. AWMA.8 pp.