The aim of this study was to evaluate the influence of temperament on body weight and reproductive performance of Nelore bulls. Temperament of 24 young bulls was assessed by chute score (CS) and flight speed (FS). Based on the results of two consecutive evaluations (M1 and M2), bulls were divided into two groups according to their CS: Reactive (n = 12) and Calm (n = 12). Blood samples were collected from both groups for testosterone and cortisol analysis once a month for 4 months. Similarly, over 4 months semen was collected along with scrotal and ocular globe thermography for further analysis, and body weight (BW) was recorded. Reactive bulls showed greater CS (P<0.0001) and FS (P<0.01) and lower BW (P<0.01) than Calm bulls. Cortisol concentrations in serum were reduced in the Calm group (P<0.05), but serum testosterone concentrations did not differ between groups with distinct behaviour. The scrotal thermography on Reactive bulls presented greater temperature at the caudal pole of testicle (P<0.05). However, semen quality (volume, kinetics, morphology and concentration) did not differ between the two groups. The results of this study demonstrated that bulls with reactive temperament were affected on their cortisol concentrations leading to loss of body weight and greater testicles temperature. The temperament of Nelore bulls had no impact on testosterone concentrations or fresh semen quality, even with increased serum cortisol and scrotal temperature.

这项研究的目的是评估气质对内罗尔公牛体重和生殖性能的影响。通过滑道得分（CS）和飞行速度（FS）评估24头公牛的气质。根据两次连续评估（M1和M2）的结果，公牛根据其CS分为两组：反应性（n  = 12）和平静（n  = 12）。两组均每月采集一次血样用于睾丸激素和皮质醇分析，为期4个月。同样，在4个月的时间里，收集精液以及阴囊和眼球热成像仪进行进一步分析，并记录体重（BW）。反应性公牛表现出较高的CS（P <0.0001）和FS（P <0.01）和较低的BW（P<0.01）比公牛冷静。镇静组的血清皮质醇浓度降低（P <0.05），但行为不同的组之间血清睾酮浓度没有差异。反应性公牛的阴囊热成像显示睾丸尾极的温度更高（P <0.05）。然而，两组的精液质量（体积，动力学，形态和浓度）没有差异。这项研究的结果表明，具有反应性气质的公牛的皮质醇浓度受到影响，导致体重减轻和睾丸温度升高。Nelore公牛的性情对睾丸激素浓度或新鲜精液质量没有影响，即使血清皮质醇和阴囊温度升高也没有影响。