Biometeorological insights into seasonal skin and coat adaptation in hairy goats from a semi-arid equatorial region

The present study aimed to analyze annual variations in coat and skin characteristics of two goat breeds raised in an equatorial semi-arid environment. Samples were obtained from 50 multiparous does (25 Canindé and 25 Moxotó), evaluated quarterly over a one-year period. The following parameters were assessed: coat thickness (mm), hair density (hairs cm−²), and hair diameter and length (mm). Skin thickness was measured in micrometers (µm), as well as the area of sweat glands and cutaneous blood capillaries, expressed in µm cm−². The highest ambient temperatures and mean solar radiation were recorded between September and December. Significant differences (P < 0.05) were observed across periods for coat thickness, hair density, diameter, and length, as well as for the areas of cutaneous blood capillaries and sweat glands. In September, overall cutaneous thermal insulation in both breeds was reduced, which was associated with lower hair density and increased areas of blood capillaries and sweat glands (P < 0.05). It can be concluded that, under equatorial conditions, phenotypic adjustments in the morphological traits of the skin and coat contribute to the modulation of thermal insulation in goat breeds. Both Canindé and Moxotó goats adjusted insulation-related traits throughout the year. However, although both breeds exhibited marked phenotypic plasticity, Canindé goats showed greater variation in coat traits, suggesting distinct adaptive strategies in response to the environmental seasonality of the equatorial semi-arid region.