Estimativa das trocas de calor e da temperatura retal de caprinos mestiços Boer mantidos em diferentes condições térmicas.

Abstract

The exposure of goats to high air temperatures can induce an increase in body temperature, resulting in physiological damage to the animals. The present research had as objective to estimate the total heat exchanges and the rectal temperature, and to quantify the thermal stress levels suffered by crossbred ¼ Boer + ¼ goats with no defined racial pattern (SPRD) submitted to different air temperatures in the chamber climate change. Six animals were distributed in a completely randomized design and subjected to air temperatures of 26, 30 and 34 °C, respectively, with relative humidity of 68%. Data of rectal temperature (RT), respiratory rate (RF) and thermograms of the animals were collected at each air temperature evaluated. In the thermograms, the temperatures of the ocular globe (PT), head (HT), shoulder (ST), hindquarter (HQ), maximum infrared temperature (TMax) and mean surface temperature (TS) of the animals were collected. Temperature and humidity index (ITU) values were calculated and the sensitive heat (convection and radiation) and latent (respiratory and cutaneous tract) heat losses of the animals were estimated for the three air temperatures tested. The correlation and agreement of the data of PT, HT, ST HQ and TMax with the TR and the correlation of the heat loss intensity of the animals by each one of the ways evaluated with TR, TS and FR were evaluated. The ITU values were classified in the categories of thermal comfort (74.8), moderate stress (80.3) and very stressful (85.6), respectively, in the three conditions evaluated, where there was an increase in TR, TS and FR.