Gaseous Emissions from Swine Facilities Following Feedingof Low Crude Protein Diets

摘要

An environmental facility at Iowa State University was constructed to evaluate the impact of dietmodification on air emissions. The facility was designed and constructed to have the uniqueability to house cattle, poultry and swine by incorporating interchangeable penning and wateringsystems. Excreta volumes can be measured for group-housed animals. Gas emissions aredetermined by measuring airflow rates through each of the eight animal chambers andmultiplying airflow by the concentration of the gas as it is measured in the chambers’ exhaustair. Chambers are monitored sequentially, for 15 min each, with incoming air measuressubtracted from chamber measures, providing 10-11 observations per chamber each day. Eachchamber is independently heated or air conditioned based on a temperature setpoint. Dataacquisition is coordinated through software control, including an emergency alarm system shouldventilation problems arise. A swine study has been conducted in the facility to evaluate the effectof feeding reduced crude protein diets on air emissions. Results demonstrated that the lowestcrude protein diet reduced ammonia concentrations by 36% and ammonia emissions by 45%with no detrimental impact on animal performance. Hydrogen sulfide emissions were unaffectedby dietary treatment. Findings from the first study conducted in the facility indicate that thisfacility can discriminate between emissions from animals fed diets that are modified to reducenutrient excretions while maintaining animal performance.