Pereira, Danilo Florentino [UNESP]do Vale, M. M.Zevolli, B. R. [UNESP]Salgado, D. D.2014-05-202014-05-202010-10-01Brazilian Journal of Poultry Science. Campinas: Facta-fundacio Arnco Ciência Tecnologia Avicolas, v. 12, n. 4, p. 265-271, 2010.1516-635Xhttp://hdl.handle.net/11449/239Layer mortality due to heat stress is an important economic loss for the producer. The aim of this study was to determine the mortality pattern of layers reared in the region of Bastos, SP, Brazil, according to external environment and bird age. Data mining technique were used based on monthly mortality records of hens in production, 135 poultry houses, from January 2004 to August 2008. The external environment was characterized according maximum and minimum temperatures, obtained monthly at the meteorological station CATI in the city of Tupa, SP, Brazil. Mortality was classified as normal (<= 1.2%) or high (> 1.2%), considering the mortality limits mentioned in literature. Data mining technique produced a decision tree with nine levels and 23 leaves, with 62.6% of overall accuracy. The hit rate for the High class was 64.1% and 59.9% for Normal class. The decision tree allowed finding a pattern in the mortality data, generating a model for estimating mortality based on the thermal environment and bird age.265-271engData mininglayer productionmortalitythermal comfortArtigoS1516-635X2010000400008WOS:000287072600008Acesso abertoS1516-635X2010000400008-en.pdf