Efeitos da tosquia nos parâmetros fisiológicos de ovelhas rabo largo criadas no nordeste do Brasil

Abstract

This study aimed to evaluate the physiological and thermal responses of Rabo Largo ewes subjected to heat stress in a semi-humid tropical climate, focusing on the effects of shearing. Five adult multiparous ewes were assessed under different environmental conditions (shade, direct sun exposure, and post-exposure) and two physical states (fleeced and shorn). Physiological parameters such as respiratory rate (RR), heart rate (HR), vaginal, rectal, and surface temperatures were measured, the latter obtained through infrared thermography. The results showed that solar radiation significantly increased physiological parameters, especially in shorn animals. Despite being more sensitive to heat, these animals demonstrated better thermal recovery. Shearing improved heat dissipation efficiency, particularly in shaded conditions, while fleece acted as a thermal barrier. Respiratory rate was the most responsive parameter to environmental variation, showing a strong correlation with surface and rectal temperatures. Regression equations were developed to estimate rectal temperature based on these parameters. Infrared thermography proved to be an effective and non-invasive tool for monitoring thermal comfort, allowing the identification of body regions with greater heat accumulation or dissipation. It is concluded that solar exposure significantly affects the physiological parameters of Rabo Largo ewes, with shearing proving ineffective in promoting normothermia. Therefore, excluding cases in which effective shade is provided throughout the day, shearing should not be recommended, and further studies are required to elucidate the role of wool in reducing heat gain in animals raised under tropical conditions.