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Thermal Comfort in Poultry Production Using Different Ventilation Systems and Litter Material

The aim of this study was to evaluate environmental thermal conditions of broiler houses when two different ventilation systems and two different litter materials were used. The experiment was carried out in four 12 m x 10 m broiler houses, internally divided into 4 pens, with 200 birds/pen. Four consecutive flocks were raised until 42 days of age, with 15 days of downtime between flocks. Treatments consisted of two ventilation systems (fixed or oscillating fans), and two litter materials (soybean straw or rice husks). Fans were activated by thermostats when temperature reached 25oC. In the center of each pen and outside the house, dry- and wet-bulb temperatures, black globe temperature, and air velocity were collected at 3-h intervals from 8 a.m. to 6 p.m. when birds were four, five, and six weeks of age. Based on the data collected at each time, globe temperature and humidity index (GTHI) and radiant thermal load (RTL), were determined. Litter temperature was collected using an infrared thermometer. Effects of flock, ventilation, litter, week, and hour, and the interactions among factors were considered in the data analysis of the internal thermal environment, using the theory of mixed models for repeated measures. For the external environment, variable means were calculated as a function of hour and week with the purpose of comparing internal thermal environment variables with those of the external environment. Ventilation provided by fixed and oscillating fans presented similar behavior, and had no effect on the studied parameters. However, both ventilation types were able to improve broiler house internal thermal conditions relative to the external environment. Air relative humidity was higher when rice husks were used as litter material.