Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment
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The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands (P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 +/- 0.13 mu m). However, the samples of sweat glands from the flank had the biggest area (43330.51 +/- 778.71 mu m(2)) and quantity per square centimeter (390 +/- 9 cm(-2)). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 +/- 1.75 W m(-2)) and possessed the highest surface temperatures (39.47 +/- 0.18 A degrees C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.