Noise analysis to evaluate chick thermal comfort Análise de ruído para a avaliação do conforto térmico de pintinhos

The relationship between thermal environment and chick performance has widely been evaluated, however the consideration that the assessment of the comfort may be estimated by interpreting both amplitude and frequency of bird vocalization under tropical housing conditions is a new concept. This research had as objective of estimating thermal comfort for chicks during the heating phase using this new concept. An experiment was carried out inside a climate controlled chamber (A) for establishing the behavioral pattern related to environmental temperature limits. Forty five chicks were reared inside a 2.3 m² box. A video camera was placed 2.0 m above the birds and the images were captured and registered in a computer. From the pattern determined in the controlled chamber an evaluation of the results was proceeded in a commercial broiler farm (experiment B) using similar bird density in order to validate the data. Environmental temperature, and both amplitude and frequency of the vocalizations of the chick group reared under heating were continuously recorded in both experiments. A correlation between group behavioral pattern and their vocalization, was found, evaluated not only by the noise amplitude but also by the noise frequency spectrum. When the thermal inertia is maintained by adequate use of curtains the birds vocalized less which is coincident with the low sudden variation of the temperature of the environmental. It was possible to estimate the thermal comfort for chicks at the heating stage by recording the amplitude and the frequency of the noise emitted by the reared group.A relação entre o ambiente térmico e o desempenho de pintinhos tem sido estudada, entretanto a consideração de que a medida de conforto térmico possa ser estimada pela interpretação da amplitude e da freqüência da vocalização, em condições tropicais de alojamento é um conceito novo. Esta pesquisa teve como objetivo estimar uma medida de bem-estar térmico para pintinhos em fase de aquecimento, pela medida de amplitude e freqüência do ruído emitido pelo grupo alojado. Inicialmente foi feito um experimento em câmara climática (A), para se estabelecer padrões de comportamento a partir de limites de temperatura ambiental. Foram alojados 45 pintos em um box de 2,3 m². Uma câmera foi colocada a 2,0 m acima das aves e a captura das imagens foi registrada em um computador. A partir dos padrões determinados no primeiro experimento, foi feita uma avaliação desses resultados em uma granja com