Inconsistency between the environments of indoor pullet rearing and adult outdoor housing may increase the fearfulness in free-range hens. Rearing enrichments and/or range use may reduce adult fearfulness. Hy-Line Brown^® chicks (n = 1700) were reared inside across 16 weeks with three enrichment treatments: weekly changing novel objects, custom-designed perching/navigation structures, or no additional enrichments. Pullets were transferred to a free-range system at 16 weeks of age, with range access provided from 25 weeks. At 62 weeks, 135 hens were selected from the three rearing treatments and two ranging groups (indoor: no ranging and outdoor: daily ranging) based on individual radio-frequency identification tracking. Individual behavioural tests of tonic immobility, emergence, open field, and novel object (pen level) were carried out on hens. Spectrograms of vocalisations were analysed for the open field test, as well as computer vision tracking of hen locomotion. The results showed few effects of rearing treatments, with outdoor rangers less fearful than indoor hens. The latency to step in the open field test negatively correlated with hen feather coverage. These results show that individual variation in ranging behaviours is present even following rearing enrichment treatments, and subsequent range use might be an indicator of bird fearfulness.

中文翻译：

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不同饲养方式下散养母鸡的范围利用与恐惧的关系

室内母鸡饲养环境和成年室外住房之间的不一致可能会增加散养母鸡的恐惧感。饲养丰富和/或放牧可以减少成年人的恐惧感。Hy-Line ^Brown®小鸡（n= 1700）在16个星期内通过三种浓缩处理饲养：每周更换新物体，定制设计的栖息/导航结构或没有其他浓缩处理。在16周龄时将小鸡转移到自由放养系统中，从25周开始提供放养。在第62周，根据个体射频识别跟踪，从三种饲养方法和两个测距组（室内：无测距，室外：每日测距）中选择了135羽母鸡。对母鸡进行了进补不动，出现，空旷和新物体（笔水平）的单独行为测试。分析了发声的声谱图，用于野外测试以及母鸡运动的计算机视觉跟踪。结果表明，养育方法几乎没有效果，室外护林员的恐惧程度不及室内母鸡。踏入野外测试的潜伏期与母鸡羽毛覆盖率负相关。这些结果表明，即使在饲养富集处理之后，测距行为也存在个体差异，并且随后的测距使用可能是鸟类恐惧的指示。