1School of Environmental and Rural Science,University of New England,Armidale,NSW 2351,Australia.
3School of Life and Environmental Science, Faculty of Veterinary Science,University of Sydney,Sydney,NSW 2006,Australia.
Animal. 2018 Mar;12(3):575-584. doi: 10.1017/S1751731117001859. Epub 2017 Jul 31.
Free-range laying hen systems are increasing within Australia. The pullets for these systems are typically reared indoors before being provided first range access around 21 to 26 weeks of age. Thus, the rearing and laying environments are disparate and hens may not adapt well to free-range housing. In this study, we reared 290 Hy-Line® Brown day-old chicks divided into two rooms each with feed, water and litter. In the enriched room, multiple structural, manipulable, visual and auditory stimuli were also provided from 4 to 21 days, the non-enriched room had no additional objects or stimuli. Pullets were transferred to the laying facility at 12 weeks of age and divided into six pens (three enriched-reared, three non-enriched-reared) with identical indoor resources and outdoor range area. All birds were first provided range access at 21 weeks of age. Video observations of natural disturbance behaviours on the range at 22 to 23 and 33 to 34 weeks of age showed no differences in frequency of disturbance occurrences between treatment groups (P=0.09) but a decrease in disturbance occurrences over time (P<0.0001). Radio-frequency identification tracking of individually tagged birds from 21 to 37 weeks of age showed enriched birds on average, spent less time on the range each day (P<0.04) but with a higher number of range visits than non-enriched birds from 21 to 24 weeks of age (P=0.01). Enriched birds accessed the range on more days (P=0.03) but over time, most birds in both treatment groups accessed the range daily. Basic external health scoring showed minimal differences between treatment groups with most birds in visibly good condition. At 38 weeks of age all birds were locked inside for 2 days and from 40 to 42 weeks of age the outdoor range was reduced to 20% of its original size to simulate stressful events. The eggs from non-enriched birds had higher corticosterone concentrations following lock-in and 2 weeks following range reduction compared with the concentrations within eggs from enriched birds (P<0.0001). Correspondingly, the enriched hens showing a greater increase in the number of visits following range area reduction compared to non-enriched hens (P=0.02). Only one rearing room per treatment was used but these preliminary data indicate 3 weeks of early enrichment had some long-term effects on hen ranging behaviour and enhanced hen's adaptability to environmental stressors.
自由放养蛋鸡系统在澳大利亚越来越多。这些系统的育雏通常在室内饲养，然后在 21 至 26 周龄左右首次进入围场。因此，育雏和产蛋环境不同，母鸡可能无法很好地适应自由放养的鸡舍。在这项研究中，我们饲养了 290 只海兰褐壳蛋鸡雏鸡，分为两个房间，每个房间都有饲料、水和垫料。在丰富的房间里，从 4 到 21 天，还提供了多个结构、可操作、视觉和听觉刺激，非丰富的房间没有额外的物体或刺激。育雏鸡在 12 周龄时转移到产蛋设施，分为六个围栏（三个丰富饲养，三个非丰富饲养），室内资源和室外围场面积相同。所有的鸡在 21 周龄时第一次被允许进入围场。在 22 至 23 周龄和 33 至 34 周龄时，对围场内自然干扰行为的视频观察显示，处理组之间干扰发生的频率没有差异（P=0.09），但随着时间的推移干扰发生的频率下降（P<0.0001）。从 21 周到 37 周龄，对单独标记的鸟类进行射频识别跟踪显示，丰富环境中的鸟类平均每天在围场内的时间较少（P<0.04），但从 21 周到 24 周龄，丰富环境中的鸟类的围场访问次数多于非丰富环境中的鸟类（P=0.01）。丰富环境中的鸟类在更多的日子里进入围场（P=0.03），但随着时间的推移，两个处理组的大多数鸟类都每天进入围场。基本的外部健康评分显示，处理组之间的差异很小，大多数鸟类的状况都很好。在 38 周龄时，所有的鸡都被关在里面两天，在 40 周到 42 周龄时，室外围场缩小到原来面积的 20%，以模拟应激事件。与丰富组鸡蛋中的皮质酮浓度相比，非丰富组鸡蛋在锁定后和围场缩小后两周内的皮质酮浓度更高（P<0.0001）。相应地，与非丰富组母鸡相比，丰富组母鸡在围场面积缩小后，母鸡的访问次数增加更多（P=0.02）。每个处理组只用了一个育雏室，但这些初步数据表明，早期 3 周的丰富环境对母鸡的围场行为有一些长期影响，并增强了母鸡对环境应激源的适应能力。
