Evaluation of the surface temperature of laying hens in different thermal environments during the initial stage of age based on thermographic images.

The initial stage of laying hens requires important care in relation to the thermal environment, in view of the good development of the birds, the obtaining of good quality pullets and, consequently, the adequate laying rate of adult birds. The aim of the present study was to study, through thermographic images, the variation of the superficial temperature of laying birds of the Lohmann LSL Lite line, from one to forty-two days of age, submitted to different thermal environments. For this experiment, 864 layer chicks were distributed homogeneously in four climatic chambers. The characterization of the different environments was as follows: thermal comfort conditions (32.8 °C–20.2 °C), two cold stress levels (28.0 °C–17.9 °C and 25.5 °C–17.3 °C) and one level of heat stress (37.4 °C–23.3 °C). The black globe temperature and humidity index (BGHI) was also calculated during the trials. The data were evaluated through the Tukey test, adopting the level of 5% of probability. Via infrared thermography the temperatures of head, body and shank of the laying birds were recorded. The results showed effect (P < 0.05) of the temperature of each environment on the surface temperature of the birds. Along with the rise of the ambient temperature, an increase in the surface temperature (head and shank) was found. Under the recommended comfort treatment, the performance of laying birds during the earlystage, related to the superficial temperature of the birds shows the best values with temperature ranges of 32.8 °C–20.2 °C and BGHI values between 82.3 ± 1.3 and 66.4 ± 1.3.