RESPOSTAS FISIOLÓGICAS E COMPORTAMENTAIS DE OVELHAS DA RAÇA MERINO SUBMETIDAS A ELEVADAS TEMPERATURAS NO AMBIENTE DO MONTADO ALENTEJANO

Abstract

This experiment was developed in three stages with 12 adults female Merino sheep, six white and six black, aiming at evaluating the differences between these breeds sheep concerning: I. Index of tolerance to heat, II. Thermic balance and heat stock circadian variation, and; III. Adaptive behavior. In the tolerance to heat, the superior stock displayed by the rectal temperatures of black sheep during their stay in the sun was worthy of notice. However, it has fast but incomplete recovery after being exposed to one hour of shade. In the same study, the sweat rates of the black sheep surpassed those of the White ones, that is, after the recovery in the shade. On circadian cycles in shade evaluations, the superiority of rectal temperatures for White sheep deserves to be highlighted. In addition, the sweat rates of the black ones surpassed those of the White ones at the hottest hours. Concerning behavior, it was also possible to notice some differences between the breeds studied here. Among them, we can highlight the superiority in terms of grazing time of White sheep. Differences between the two studied colors of Merino breed occur in the thermic balance as well as in the thermoregulating answers.