High climatic temperature is the most important factor hampering livestock productivity in tropical and arid regions. Therefore, the current study aimed to investigate the interaction between coat color and heat tolerance in two principal Saudi sheep breeds; Najdi (black colored coat) and Naemi (white colored coat). Najdi and Naemi adult sheep of different age groups and both sexes, raised under direct solar radiation in different parts of the Riyadh region were used. The thermo-physiological measurements were taken from sheep flocks raised under a similar production system in different parts of Riyadh region during the summer season. The recorded rectal temperature (T_re) was significantly (P < 0.05) higher in the white coat colored breed compared to the black coat colored breed. Consequently, the calculated heat tolerance coefficient (HTC) was significantly (P < 0.05) higher in the black coat colored breed compared to the white coat colored one. No significant (P> 0.05) differences were observed concerning skin temperature (T_sk), packed cell volume (PCV) and plasma albumin levels between the two breeds. The obtained results indicate that white coat color of sheep grazing under a hot arid climate is not a crucial trait of heat tolerance and adaptation. Other hair coat characteristics and evaporative cooling traits might play important role in the adaptation of the black coat colored sheep breed grazing under hot arid conditions.

高温是阻碍热带和干旱地区畜牧业生产力的最重要因素。因此，目前的研究旨在调查两个主要沙特绵羊品种的皮色和耐热性之间的相互作用。Najdi（黑色外套）和Naemi（白色外套）。使用了在利雅得地区不同地区在直接太阳辐射下饲养的不同年龄段和性别的纳吉迪和纳米成年绵羊。在夏季，在利雅得地区不同地区，使用相似的生产系统饲养的羊群进行了热生理测量。记录的直肠温度（T _re）显着（P<0.05），与黑色大衣相比，白色大衣的品种更高。因此，黑色外套颜色的品种比白色外套颜色的耐热系数（HTC）显着更高（P <0.05）。在两个品种之间，关于皮肤温度（T _sk），细胞堆积量（PCV）和血浆白蛋白水平没有观察到显着差异（P > 0.05）。获得的结果表明，在炎热干旱的气候下放牧绵羊的白大衣颜色不是耐热性和适应性的关键特征。其他毛层特征和蒸发冷却特征可能在热干旱条件下放牧黑色毛色绵羊品种的适应中起重要作用。