Degradation of Nitrogenous Components in and Volatilization of Ammonia from Litter in Aviary Housing Systems for Laying Hens

Abstract

Ammonia emissions from poultry houses for laying hens with litter are higher than the emissions from battery houses. The emission of ammonia must be reduced and the working environment should be improved to warrant the acceptance and sustainment of aviary houses in the future. Physical and chemical relationships of the volatilization of ammonia and the degradation of organic material in litter from aviary houses for laying hens were analyzed and verified by means of experimental data, which consisted of 66 litter samples taken from 12 commercial aviary houses. The volatilization rate of ammonia from the litter was linear to the NH3 concentration in the water of the litter, whereas the pKa of the NH3-NH4+ equilibrium was adjusted to 8.65. The concentration of total ammoniacal nitrogen (NH3+NH4+) in the litter found in the aviary houses, which is the result of the degradation of organic material, was approximately 4% higher per 1/10 unit of pH, 4% higher per unit of temperature (C), and 4% higher per 10 units of water content (g/kg). The cold winter climate appeared to have an adverse influence on the litter close to the outer walls of the aviary houses. Emissions of ammonia from litter can be reduced by maintaining a high dry matter content, a low pH or low temperature, which minimize the degradation rate of organic nitrogen and thus the volatilization of ammonia. However, control of pH and temperature may not always be possible or acceptable in aviary houses.