Características e estruturas de tegumento de ovinos mantidos em ambiente controlado.

Abstract

Thermal stress can negatively interfere with animal welfare, significantly affecting animal production. Their integuments and structural characteristics are directly related to adaptability to the climatic conditions to which they are exposed. This study aimed to evaluate variations in the morphology of the integument and fleece structures of native hair sheep subjected to different environmental conditions in a climate chamber and controlled environments. A total of 24 uncastrated male sheep from the Soinga, Morada Nova, Santa Inês, and Non-Defined Racial Pattern (SPRD) breeds were used, with six individuals from each breed, averaging five months of age (SD = 0.5 months) and an average weight of 25.0 kg (SD = 3.6 kg). The animals were exposed for 12 continuous hours (from 6:00 AM to 6:00 PM) over 15 consecutive days in each treatment (temperatures of 20.0, 24.0, 28.0, 32.0, and 36.0°C). The integument characteristics studied included epidermal area (μm²) and keratinized portion (μm²), sebaceous gland area (μm²), number of sweat glands, and number of hair follicles (primary and secondary) per unit area (cm²). The histological samples were analyzed under light microscopy using photomicrographs taken with a camera-equipped microscope at the Histology Laboratory of the Federal University of Paraíba, using the Motic Images Plus 2.0 software. The experimental design was a completely randomized design (CRD) in a factorial scheme (temperature × breed) with six replications. The data were subjected to analysis of variance (ANOVA), and the means were compared using Tukey’s test at a 5% significance level, employing the PROC GLM procedure of SAS® software. The sebaceous gland area was significantly larger in the Morada Nova breed and was affected by high temperatures, showing a 67.9% increase between 20.0 and 36.0°C in the average gland area. Epidermal thickness increased at 36.0°C, particularly in the Morada Nova breed. Hair length, average hair count, and numerical hair density were lower in the Morada Nova breed. The Morada Nova breed demonstrated better adaptation to thermal stress by modifying fleece structure and skin morphology.