ABSTRACT

The relationship between hair color characteristics and thermoregulatory responses in ewes raised in hot environment were evaluated. 15 Santa Inês hair ewes of different genotypes associated with coat colors (light brown, dark brown and black) with body weight of 41.2 ± 8.1 kg were evaluated during three consecutive days. Rectal temperature (R_T, °C) and coat surface temperature (C_ST, °C) of seven anatomical points (front, back, croup, loin, side, thigh, and belly) were measured during the morning and afternoon periods. Thermoregulatory responses were recorded along with meteorological variables. Heat tolerance index (H_TI) and thermal gradient (T_G, °C) were estimated for each genotype. R_T and C_ST were influenced by periods of the day (P < 0.05), being higher in the afternoon, but T_G did not differ (P > 0.05) between periods. H_TI, C_ST, and T_G were equal (P > 0.05) among the three genotypes. Only R_T was higher in animals with dark brown coats compared to light brown, but equal to the black coat. It was observed that animals with black or dark brown hairs have a strong association between the C_ST under study, and yet these had an inverse behavior with the R_T. Animals with a darker coat tend to trigger heat dissipation in various anatomical regions of the body, presenting dynamics in thermoregulatory responses in relation to those with lighter coats. Santa Inês ewes have heat dissipation mechanisms as a function of different genotypes associated with coat colors, but have the same thermoregulatory aspects to maintain homeostasis, demonstrating an excellent adaptive mechanism in a hot environment.

摘要

评估了在炎热环境中饲养的母羊的毛发颜色特征与体温调节反应之间的关系。在连续三天内评估了15只与毛色（浅棕色、深棕色和黑色）相关的不同基因型的圣伊内斯毛母羊，体重为 41.2 ± 8.1 kg。在上午和下午期间测量了七个解剖点（前部、背部、臀部、腰部、侧面、大腿和腹部）的直肠温度（R _T，°C）和皮毛表面温度（C _ST，°C）。体温调节反应与气象变量一起被记录下来。耐热性指数（H _TI）和热梯度（T _{g ^}，℃）估计每种基因型。[R _Ť和 C _ST受一天中的时段影响（P < 0.05），下午较高，但 T _G在时段之间没有差异（P > 0.05）。ħ _TI，C _ST和T _{g ^}相等（P > 0.05）的三种基因型中。与浅棕色相比，深棕色皮毛的动物中只有 R _T更高，但与黑色皮毛相等。据观察，黑色或深棕色毛发的动物在研究中的 C _ST之间有很强的关联，但这些与 R _T有相反的行为. 皮毛颜色较深的动物往往会触发身体各个解剖部位的散热，与皮毛颜色较浅的动物相比，体温调节反应呈现动态。Santa Inês母羊具有散热机制，作为与毛色相关的不同基因型的函数，但具有相同的体温调节方面来维持体内平衡，在炎热环境中表现出极好的适应机制。