Thermoregulation of male sheep of indigenous or exotic breeds in a tropical environment

摘要: Climate change has intensified the frequency of heat waves in world, thereby exposing farm animals to stressful conditions. For better productive performance it is important identify most resilient genotypes. Thus, our objective was evaluate thermoregulatory responses rams tropical indigenous (Morada Nova and Santa Ines) exotic breeds (Dorper Texel), by monitoring environmental physiological indicators related tolerance. The experiment carried out a climate region (Cwa), Brazil, for twelve months, which comprised spring, summer, autumn winter. Thirty-three were divided into groups: Morada (MN; n=8, red-coat), Ines (SI; n=9, black-coat), Dorper (DO; white-coat) Texel (TX; white-coat). microclimatic variables monitored, THI BGHI comfort indices calculated. Coat thickness body surface temperatures measured monthly, serum triiodothyronine-T3 measurements complete blood tests performed. evaluated every fifteen days skin micro-biopsies performed summer winter histological evaluation. During warmer seasons, reached values that indicated thermal discomfort. TX showed higher coat throughout year, increased thermolysis, reduced T3 (P < 0.05). internal temperature permanently lower MN, SI DO affected characteristics wool length. Hematological parameters varied seasons with highest conditions MN larger sweat glands, while area occupied glands SI. hair density results overcome challenge more easily due specific adaptive morphological characteristics.