Determinação de um índice de conforto térmico para ovinos da raça Dorper

Abstract

Twenty Dorper sheeps were observed with a mean age of 20 months, males, intact, in the Arcoverde town, Pernambuco State, Brazil aiming to develop a thermal comfort index using multivariate analysis. The animals were maintained in covered installations in feedlot system and physiological reactions as rectal temperature (RT, °C) and respiratory frequency (RF, mov min-1 ) were avaliated under shade in the morning (6h30min.) and afternoon (12h30min). The new equation of thermal comfort index is for Dorper sheep was ICTD= Ta × 0.46956 + Bgt × 0.47194 + vv × 0.19221, where Ta is the air temperature (° C) Bgt is the black globe temperature (° C) and vv is the wind speed (m / s). The index was compared with the Temperature and Humidity Index and Thermal Comfort Index, showing high correlations with RF (r = 0.6910) and RT (r = 0.3360). The estimated critical limits for the ICTD were 31.0 and 23.9, based on the RT and RF respectively.