TEMPERATURE-HUMIDITY INDEX AND THERMAL COMFORT OF BROILERS IN HUMID TROPICS.

Abstract

In improving broiler welfare and ensuring better productivity thermal comfort of broilers is of utmost interest. To estimate the thermal comfort of broilers, the THI model was developed using commonly available meteorological parameters, namely temperature and relative humidity. This research re-examined the model by using the Levenberg-Marquardt Algorithm (Excel Solver) based nonlinear regression model to reduce the error space and generate new model constants unique to Akure, South West, Nigeria. Physiological data (cloacal temperature and body weight) were collected for a period of 6 weeks from 50 broilers raised in a developed adaptive poultry housing. Environmental data on temperature and relative humidity were used to calibrate the THI of the broilers. For the period of the study cloacal temperature ranged between 39.38 and 42.60 ^oC while average final weight of broilers was 4.0 kg. Five THI models were developed taking into account the environmental conditions, all five developed model equations showed an improved performance when compared with the calibrated and the existing model based on the high value of the degree of accuracy (R²) of 99.95%, 99.94%, 100.00%, 99.93% and 99.94% for the hourly, daily, morning, afternoon, and evening environmental conditions respectively. The validity of the established THI models shows a very high linearity with high degree of accuracy (R²> 99%). These equations indicate that broilers reared in the humid tropical environment were affected more by dry bulb temperature than by relative humidity.