Sensible and latent heat productions from broilers in laboratory conditions

Heat production from chickens and other resources inside the broiler house is a major problem for the broiler industry. Temperature and relative humidity (RH) as well as airflow and broiler physiology directly affect heat production in broiler houses. This study was carried out under laboratory conditions to determine heat production for male broilers. In the laboratory experiment, 108 broilers were used to determine the influence of different temperature-humidity combinations on the physiological response of 2.0 to 2.3 kg broilers during the 40 min test. In the laboratory experiment, three dry bulb (DB) temperatures (25 degrees C, 30 degrees C, and 35 degrees C) and three RHs (50%, 70%. and 90%) were used in a block design with four replications, 3 birds per test. DB and wet bulb (WB) temperatures of air entering and exiting the chamber were measured. Before and after each test, body temperatures were measured to control the stress level, and sensible heat production (SHP) and latent heat production (LHP) were calculated based on DB and WB temperatures. It was found that SHP decreased when the temperature and humidity combination increased. When initial DB temperature was 24.8 +/- 0.2 degrees C and RH was 71%, SHP and LHP were 2.1 +/- 0.3 W/kg and 4.0 +/- 0.4 W/kg respectively. Increasing RH 50% to 86%, decreased the LHP from 5.7 +/- 0.6 to 3.0 +/- 1.0 W/kg at the 24.8 degrees C. Latent heat production increased as DB temperature increased at 50% and 70% RH. At 90% RH, latent heat loss was zero for both 30 and 35 degrees C. Results also showed that broiler body temperature difference (BTD) increased when initial dry bulb (IDB) and initial relative humidity (IRH) combinations increased.