Abstract
The sweat glands are important in thermoregulation of cattle in a warm environment as they help dissipate heat through evaporation. Studies on gland histology are important to define its secretion potential and the capacity of perspiration and heat removal. The objective of this study was to determine, by histomorphometry, glandular epithelium height, the depth of the gland, length of the glandular portion and number of glands per cm2 of the sweat glands of the three age groups of Nellore cattle. Thirty females were used in this study. They were equally divided into calves, heifers and cows. Histological sections were obtained and analyzed by digital images in Trinocular BX40 Olympus microscope coupled to an Oly - 200 camera, connected to a computer. The images were obtained with microscope with 2x, 4x, 10x and 40x magnification objectives. The measurements were performed using HL Image 97 program. The height of glandular epithelium, depth of the glands, length and density of the glandular portion per cm2 , were all analyzed. The calves showed greater height of the glandular epithelium than heifers (P = 0.0024), and cows (P = 0.0191). The depth of the gland was not influenced by age. Cows had higher length of secretory portion than heifers (P = 0.0379) and calves (P = 0.0077). Heifers had a greater number of sweat glands per cm2 of skin than cows (P = 0.023). In cattle, the height of glandular epithelium and the density decreases as animals get older. On the other hand, the length of the secretor portion increases but with no changes in the depth of the sweat glands
Highlights
Cattle are homoeothermic animals, their body temperature is kept constant even under variations in environmental conditions because they are able to regulate the production and loss of heat
Palavras-chave: Bos indicus, epitélio glandular, microscopia, histomorfometria, glândula sudorípara. Their body temperature is kept constant even under variations in environmental conditions because they are able to regulate the production and loss of heat. This ability in regulating body temperature may be affected by environmental factors and those related to the animal
The cattle kept in warm environments display physiological alterations when trying to reach thermal balance
Summary
Their body temperature is kept constant even under variations in environmental conditions because they are able to regulate the production and loss of heat. This ability in regulating body temperature may be affected by environmental factors and those related to the animal. Regarding the former, solar radiation, the number of animals per square meter and humidity, temperature and air velocity are some examples. Body cooling by cutaneous evaporation is the most effective way to dissipate heat and the sweat glands play an important role in this process, being paramount to the adaptation of ruminants to the tropical environment (Salimos, 1980)
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