Locally adapted goats efficiently gain and lose heat in an equatorial semi-arid environment

Abstract

The aim of this study was to gain insights in respect to how locally adapted goats exhibit dynamic body heat in an equatorial semi-arid environment. Ten Canindé goats were used in the study (22.90 ± 2.70kg). Respiratory rate (RR; min breaths-1), rectal temperature (RT; °C) and sweating rate (SR; gm-2h-1) were measured for 8days, once a week, for 8 consecutive weeks in each animal, with collection intervals of 1h throughout the day (24h), together with the meteorological variables. Air temperature (AT, °C) and relative humidity (RH, %) were measured, and then, the temperature humidity index (THI) was calculated. First, we determined 2days with stressful climatic conditions and similar environmental characteristics (day 1 and 2) among the 8 experimental days. The RT was evaluated on these 2days using the means of each hour as the cut-off point, and determining whether the animals are efficient (EF) or inefficient (INEF) in heat loss (β1) and gain (β2). The RT was separated in β1 and β2 for 24h, setting times to obtain the angular coefficients (β) for both. The days with stressful climatic conditions and similar environmental characteristics were day 1 and 2. The hours in which the Canindé goats gained and lost heat were respectively 11 a.m. to 3 p.m. and from 4 p.m. to 10 a.m. The animals classified as EF lost more or equal the amount of heat represented for RT. When the mean of all animals was evaluated for efficiency in heat control, the flock was classified as EF. Differences (P < 0.05) were observed for RR and SR between periods. The efficiency in dynamic body heat of the locally adapted goats in this study was determined and showed that the flock as a whole possesses an excellent heat dynamic in an equatorial semi-arid environment.