Nitrogen mass balance in commercial roaster houses receiving different acidifier application rates

Abstract

Broiler production has the potential to cause water and air pollution. Acidifiers such as sodium bisulfate (SBS) can reduce ammonia (NH3) emissions from broiler houses; NH3 is an important air pollutant that also affects bird health. Due to their longer grow-outs, roasters may require higher acidifier application rates to prevent unhealthy NH3 levels during the flock than ordinary broilers. Changes in NH3 emission with acidifier use may affect the partitioning of the input nitrogen (N) among the different N output pathways. Accounting for these output pathways through N mass balance provides a complete picture of N as it cycles through the roaster house. In a 2-yr study involving 9 flocks of roasters, 4 levels of SBS were applied to the litter in commercial roaster houses. Whereas the control treatment received up to 0.49 kg/ m2 to the brood chamber, the high, medium, and low treatments received up to 1.46, 0.73, and 0.49 kg/m2, respectively, to the whole house. Ammonia-N emission decreased and N removed in cake and litter increased with SBS application rate. Nitrogen output components were averaged over the 4 treatments and expressed as percent of total N input or per unit mass of live weight (LW). Ammonia-N emission during grow-out, bird N exported, and cake and litter N removed accounted for 17.3% or 11.2 g/kg of LW, 38.9% or 25.1 g/kg of LW, and 22.4% or 14.4 g/kg of LW, respectively. We accounted for 79.1% of the total N inputs, with NH3-N losses during layout probably constituting the bulk of the unaccounted N. In addition to uncertainties in measurements of inputs and outputs, other factors that limited the ability to close the N mass balance were exclusion of feathers during cake and litter sampling, soil N leaching, and nitrous oxide emissions. © 2013 Poultry Science Association, Inc.