Concentração e emissão de amônia em aviários de frango de corte

Abstract

The aerial environment in broiler houses requires differentiated management depending on the time of year to maintain an ammonia concentration below 10 ppm, optimal condition for broilers, and adequate performance and well-being. The ammonia is volatilized from the microbial decomposition in the poultry litter and dependent on several factors, among them, internal and external environmental conditions, litter characteristics and facility typology. The systematization and analysis of data can help in to understanding studies that contain a variability of interferences, like an aerial ambience; and a data mining is a technique that has the function of analyzing the generated database. Three studies were carried out to evaluate the production of ammonia in broiler houses in conditions of heat and mild climate, by means of meta-analysis and environmental measurement. The first study resulted in an ammonia concentration database using the meta-analysis technique. Data analysis was with data mining technique, using two ammonia concentration classes: less than 20 ppm and equal or above this limit. Negative pressure facilities presented high ammonia concentration and morning time presented an ammonia concentration equal or above 20 ppm. Conventional facilities, using wood shavings and stoking density whit more than 15 birds m-2 had an ammonia concentration classification above the ideal limit (≥ 20 ppm). The second study provided a meta-analysis of the ammonia emission that allowed, through the data mining technique, to obtain two classification approaches: a) high ammonia emission levels (≥ 42.2 mg Kg-1 of poultry litter) and b) low ammonia emission levels (<42.2 mg Kg-1 poultry litter). Only Dark House was qualified for “High” ammonia emission due the winter season. The wood shavings poultry litter presented low emission when in conventional houses, in contrast to rice husk (high ammonia emission). Poultry litter whit above 8.3 and stocking density greater than 12 birds m-2 obtained “High” ammonia emission classification. In the third study the ammonia concentration, air velocity, internal and external temperature were collected in six broiler houses of different typologies and climatic conditions of heat, being analyzed by geostatistics. The concentration of ammonia tends to be higher in the central and final part of the broiler houses, places where the internal temperature was higher. Better ventilation maneuvers could solve the problems with high temperature and ammonia concentration throughout the broiler houses. The results observed in the concentration and ammonia emission meta-analysis point to conditions of facilities and characteristics of the poultry litter. Data mining allowed the evaluation of ammonia production in different typologies of aviaries in a systematic way through two databases constructed by the meta-analysis technique. The rules of the figure models allowed extracting coherent and useful knowledge in meta-analysis databases. The use of maps of variability is another suitable means for the evaluation of variables such as ammonia concentration and internal temperature. However, several factors influence and, if handled correctly, can minimize the emission and concentration of ammonia inside the broiler house. Combining the thermal and aerial ambience with the ventilation system is an option to improve the welfare indexes in broilers.