Effects of Dietary Modification on Laying Hens in High-Rise Houses: Part I – Emissions of Ammonia, Hydrogen Sulfide and Carbon Dioxide
Dietary manipulation can substantially lower ammonia (NH3) emissions from laying-hen houses or manure storage. Recent lab studies showed a reduction of 40–60% in ammonia emissions for an experimental (EcoCalTM) diet as compared the standard or control diet. However, adoption of a mitigation technology at commercial production level should be preceded by substantial field verification tests to document not only NH3 emission reduction, but also impact of the strategy on production performance of the hens and cash returns. A study to assess the effects of feeding diets containing EcoCal on NH3, hydrogen sulfide (H2S), and carbon dioxide (CO2) emissions, laying-hen production performance, and economic returns was conducted at a commercial laying-hen farm in central Iowa. Two houses (256,000 or 262,000 hens per house) were used for the study. Hens in one house were fed the EcoCal diet while hens in the other house were fed a standard or control diet containing no EcoCal. A state-of-the-art mobile air emissions monitoring unit (MAEMU) and the associated sampling system were used to continuously monitor the gaseous concentrations, ventilation rate and environmental conditions. Comparative data collected from December 2006 to May 2007 are presented in this paper. Data from this period showed that the EcoCal diet led to NH3 emission reduction by up to 23.2% (0.86±0.04 and 1.12±0.03 g/d·hen for EcoCal and Control diet, respectively), at the same time, H2S emission increased by up to 134% (4.38±0.20 and 1.82±0.07 mg/d·hen for EcoCal and Control diet, respectively), although the magnitude of H2S emission is rather small for both dietary regimens. Data on the hen production performance are reported in a companion paper (Roberts et al., 2008).
Development and Testing of a Fan Monitoring System Using Induction Operated Current Switches
Emissions of gaseous compounds and particulate matter are the product of the pollutant 
concentrations and air exhausted from the fans of mechanically ventilated animal confinement 
buildings. Direct methods of monitoring exhaust fan operation (i.e., mercury tilt, limit or whisker, and 
vibration switches) have been reported to have limitations due to mechanical failure and/or the effect 
of the environment (dust, wind, moisture). Another method involves monitoring the control relay 
status at the fan system control box. A problem could occur at the fan but not in the signal at the 
control box, thereby giving a false operational signal. The objective of this project was to find a more 
reliable method of monitoring fan operation status. This paper describes the development, lab 
testing, and use of a fan monitoring system based on induction operated current switches (ICS). 
ICSs are unaffected by the environment and can provide direct measurement of real-time fan operational status by sensing AC current. A laboratory test of the ICS was performed to simulate a 
fan off/on duty cycle in a two-year emissions study; no ICS failure was recorded. The Southeastern 
Broiler Gaseous and Particulate Matter Emission study led by Iowa State University has been using 
28 ICSs for over 190 days without a failure. At a unit cost as low as $19.50 this method offers a 
reliable, accurate, and economical way of measuring the real-time operational status of ventilation 
fans – a critical component of any air emissions monitoring in a mechanically ventilated confinement 
system.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.