Brief Summary of Minutes of Annual Meeting

Accomplishments I. Poultry House Environment IA, KY and PA continued to collaborate on a multi-state, multi-disciplinary research project that aims to characterize and quantify aerial ammonia (NH3) emission rate (ER) from selected US poultry (broiler and laying hens) facilities with different housing and management schemes. Data collection, covering one-year period, was completed and manuscripts summarizing the research findings for journal publication have been prepared and/or accepted. Manure handling practices and dietary CP content affected NH3 ER. Specifically, NH3 ER during the 12-month monitoring period averaged 0.90 (±0.24) and 0.81 (±0.21) g d-1 hen-1 for the high-rise layer houses in IA with standard diet and reduced crude protein diet, respectively; 0.83 (±0.35) g d-1 hen-1 for the PA high-rise layer houses with standard diet; and 0.054 (±0.026) and 0.094 (±0.062) g d-1 hen-1 for the IA and PA belt houses with manure removed daily and twice a week, respectively. Results of the study contribute to the U.S. national inventory on NH3 emissions from animal feeding operations, and characterize dynamics and magnitude of NH3 emissions from U.S. layer houses as affected by housing type, manure management, diet manipulation and geographical location. IA, KY and PA compared building ventilation rates obtained by direct measurement and by a CO2 balance. The test was conducted at a commercial laying hen house that used a manure belt with daily manure removal. The results indicate that ventilation rates estimated by the indirect method were not significantly different (P>0.2) from those as determined by the direct measurement when the averaging or integration time interval was two hours or longer. Careful application of the indirect method could greatly improve the affordability and versatility of endeavors toward quantifying air emissions from confined animal housing. IA evaluated the operational performance of Single Point Monitors (SPMs) for measuring aerial ammonia (NH3, 0 to 30 ppm) and hydrogen sulfide (H2S, 0 to 90 ppb) under laboratory and field conditions. The SPMs were evaluated against a chemiluminescence NH3 analyzer or a pulsed-fluorescence H2S analyzer. SPM readings of H2S or NH3 gas concentrations increase with moisture content of sample air. Compensation for this moisture dependence can be made for H2S gas measurement with an overall correctional equation to generally achieve 90% to 107% agreement with readings measured by the pulsed-fluorescence analyzer. In comparison, such correctional compensation was not effective for NH3 measurement (59% to 90% agreement). Knowledge of moisture content in sample air is necessary to compensate for the moisture interference. The SPMs showed weak interchangeability, especially for NH3 measurement; however they showed a good stability over the 8-month testing period. IL has completed work on ammonia generation from layer hens. During the first two weeks of composting, laying hen manure generates gaseous ammonia at rates comparable to manure that is collected under cages. However, as composting time increases ammonia generation rate significantly decreases. These data will be used to establish the beneficial effects of composting for reducing total ammonia generated from laying hen production units. Economic value of composted manure can also be used in for inclusion into models that can be used for business decisions. II. Behavioral Responses IA quantified the effects of cage stocking density (348, 387, 426, and 465 cm2 per hen; 54, 60, 66, and 72 in2 per hen) on the feeding behavior of the W-36 White Leghorn laying hen. Feeding behaviors were characterized using a specialized instrumentation system and computational algorithm. No significant differences detected among the stocking densities under thermoneutral conditions with regard to daily feed intake, hen-hours spent feeding per cage, average feeding time per hen, number of meals ingested per day per cage, meal size in g/meal-hen, average meal duration in sec/meal, ingestion rate in g/min-hen, or average number of hens feeding per meal. Quantification of specific responses such as feeding behavior to potential stressors (i.e. cage stocking density) may yield better housing design and management decisions based upon scientific data to improve animal welfare. III. Physical Environment Responses An economic analysis at MI of the increase in cage space required for laying hens under new animal well-being guidelines approved by United Egg Producers. An increase in cage space from 48 in2 to 67 in2 will cost 5.9 cents/dozen in net receipts per 1000 ft2 of cage space. At an assumption of 80 cents for a dozen eggs, a 1% change in egg price will be offset by a change in the opposite direction of 4% in layer feed cost or 12% in pullet prices. IV. Nutritional Responses MN in cooperation with MI examined the influence of assigning different energy values to corn distillers dried grains with solubles in grow-finish turkey diets. Energy content as determined by the true metabolizable energy methodology overestimated the energy value especially when DDGs was included at 20% of the diet. However, the overestimation of energy while negatively affecting feed conversion tended to better support weight gains at the higher level of DDGs inclusion for turkeys fed under summer time conditions. MI evaluated the use of 25-hydroxycholecalciferol in broiler starter diets can reduce the incidence of tibial dyschondroplasia in Ross cockerels when dietary calcium is fed at 0.85% or less. The use of ultraviolet light to improve phytate phosphorus utilization in broilers is only useful when low levels of cholecalciferol, calcium and phosphorus are fed. Estimates of apparent metabolizable energy of corn distillers dried grains with solubles (DDGS) with laying hens and five-week-old turkey poults in a MI study showed that DDGS derived from new technology in the ethanol industry has about a 13% higher energy content (2750 kcal/kg) than the current National Research Council (NRC) estimate for poultry. Availability of phosphorus to turkey poults is also higher than 54% which is the assumption by NRC. IL studies indicated that feeding molt diets containing high trypsin inhibitor soy hulls did not negatively affect postmolt performance. In addition, feeding molt diets containing wheat middlings, rice hulls, or soy hulls combined with corn are effective non-feed removal methods for molting laying hens. V. Physiological Responses Tom strain trials at MI demonstrated differences in commercial turkey strains over time (1999 to 2003) and between breeder companies. The first study resulted in no significant differences between growth performance and carcass characteristics between B.U.T.A. Big 6, Hybrid Converter or Nicholas 700 toms. The 2003 study showed differences in slower overall growth and higher livability for Hybrid Converter toms compared to Nicholas 700 toms. A new strain, B.U.T.A. T2, grew to a larger market weight and had higher breast yield compared to the Hybrid and Nicholas strains. The use of a scale connected to the Command II computer system in one pen demonstrated that the computer measurements were a reliable estimate of actual bird weights. VI. Data Analyses and Design The accurate and precise fitting of observed growth data with growth models is necessary to gain a mathematical understanding of the biological relationship between animals and their physical environment. Researchers have shown that some of the commonly used growth models do not represent observed growth responses. The research at the USDA-ARS Poultry Research unit at Mississippi State, MS involved the examination of genetic algorithms (GA), a procedure from the artificial intelligence discipline, as a mathematical modeling approach to fitting nonlinear growth equations. The GA was chosen for its ability to model very complex data. The GA results were compared to those obtained with traditional nonlinear regression. The results showed that genetic algorithms fit the observed data equally as well as regression analysis. However, the oscillatory nature of the difference between the observed and predicted growth responses was still present. It was concluded that the fitting of the growth equations was not so much a problem with the fitting methodology as it is with the form of the equation. Thus the form of growth equations will have to augmented to more precisely account for the oscillatory nature of the difference between predicted and observed growth responses.