SILVA, R. S.; http://lattes.cnpq.br/5199041160873620; SILVA, Ricardo de Sousa.
Résumé:
Sheep, when exposed to high temperatures, as occurs in arid and semi-arid regions, can
activate physiological and thermoregulatory mechanisms to increase the dissipation of
body heat in latent form, aiming to maintain homeothermia, with heat stress being a
significant factor that limits the improvement of sheep in their genetic potential for
production and reproduction and, when their ideal temperature is changed, the organism
may suffer some type of interference. Therefore, the objective of the research was to
quantify the levels of thermal stress, losses of sensible and latent heat in sheep native to
the Brazilian semi-arid region, kept in a climatic chamber and subjected to three
thermoneutral temperatures (TTN of 20, 24 and 28 °C) and two of thermal stress (TES of
32 and 36 °C). The experimental design used was completely randomized in a factorial
scheme, with five temperatures and twenty-four animals. It was observed that with the
increase in temperature, the animals significantly (P<0.05) increased rectal and
superficial temperatures and respiratory rate. In TTN, sensible heat exchanges
corresponded, on average, to 79.64%, while in TES to 20.36%, with latent heat exchanges
being 19.73% in TTN and 80.27% in TES. At the highest temperature (36 °C), 95.87%
of thermal exchanges were through latent media. Sheep kept in stressful thermal
conditions lost the majority of excess metabolic heat by latent means through the skin and
respiratory tract.
