Access to an outdoor range has many potential benefits for laying hens but range use can be poor due to factors only partly understood. Techniques to monitor individual range use within commercial flocks are crucial to increase our understanding of these factors. Direct observation of individual range use is difficult and time-consuming, and automatic monitoring currently relies on equipment that is difficult to use in an on-farm setting without itself influencing range use. We evaluated the performance of a novel small, light and readily portable light-based monitoring system by validating its output against direct observations. Six commercial houses (2000 hens/house) and their adjacent ranges were used, three of which were equipped with more structures on the range than the others (to determine whether cover would influence monitoring accuracy). In each house, 14 hens were equipped with light monitoring devices for 5 discrete monitoring cycles of 7 to 8 consecutive days (at 20, 26, 32, 36 and 41 weeks of age). Light levels were determined each minute: if the reading on the hen-mounted device exceeded indoor light levels, the hen was classified as outside. Focal hens were observed directly for 5 min/hen per week. Accuracy (% of samples where monitoring and direct observations were in agreement) was high both for ranges with more and with fewer structures, although slightly better for the latter (92% v. 96% ± 1 SEM, F1,19 = 5.2, P = 0.034). Furthermore, accuracy increased over time (89%, 94%, 95%, 98% ± 1 SEM for observations at 26, 32, 36 and 41 weeks, respectively, F3,19 = 3.2, P = 0.047), probably due to progressively reduced indoor light levels resulting from partial closing of ventilation openings to sustain indoor temperature. Light-based monitoring was sufficiently accurate to indicate a tendency for a greater percentage of monitored time spent outside when more range structures were provided (more: 67%, fewer: 56%, SEM: 4, $\chi_1^2 = 2.9$, P = 0.089). Furthermore, clear and relatively consistent individual differences were detected. Individuals that were caught outside at the start of the experiment ranged more throughout its duration (caught outside: 72%, caught inside 51%, SEM: 4, $\chi_1^2 = 10.0$, P = 0.002), and individual range use was correlated between monitoring cycles (for adjacent monitoring cycles: $r_s^2 = 0.5-0.7$, P < 0.0001). This emphasizes the importance of studying range use on an individual level. In conclusion, our light-based monitoring system can assess individual range use accurately (although accuracy was affected by house characteristics to some extent) and was used to show that both cover availability and individual characteristics affected range use.

中文翻译：

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基于光的监控设备，可评估蛋鸡的产蛋量。

进入户外牧场对蛋鸡有很多潜在的好处，但是由于仅仅部分被理解的因素，牧场的使用可能会很困难。监控商业鸡群中个体牧场使用情况的技术对于增进我们对这些因素的理解至关重要。直接观察单个范围的使用既困难又费时，并且自动监视当前依赖于难以在不影响范围使用的情况下在农场环境中使用的设备。我们通过对照直接观察来验证其输出，评估了新颖的小型，轻便便携式光监控系统的性能。使用了6座商品房（每只2000只母鸡）及其相邻的鸡舍，其中3座在鸡舍上配备了比其他鸡舍更多的结构（以确定遮盖是否会影响监测精度）。在每间鸡舍中，有14头母鸡配备了光监测设备，用于连续7至8天（20、26、32、36和41周龄）的5个离散监测周期。每分钟确定光照水平：如果安装在母鸡上的设备的读数超过室内光照水平，则将母鸡分类为室外。每周直接观察母鸡5分钟/只母鸡。对于结构更多和更少的范围，准确性（在监测和直接观察相符的样品中所占的百分比）均很高，尽管后者的准确性略高（92％vs. 96％±1 SEM，F1,19 = 5.2，P = 0.034）。此外，精度会随着时间的推移而提高（在26、32、36和41周观察时，分别为89％，94％，95％，98％±1 SEM，F3,19 = 3.2，P = 0.047），可能是由于通风孔的部分关闭以维持室内温度而逐渐降低室内光线水平所致。当提供更多的射程结构时，基于光的监视足够准确，表明有更多百分比的监视时间在户外使用（更多：67％，更少：56％，SEM：4，\ chi_1 ^ 2 = 2.9 $， P = 0.089）。此外，检测到明显且相对一致的个体差异。在实验开始时被外部捕获的个体在其整个持续时间内的分布范围更大（外部捕获：72％，内部捕获51％，SEM：4，$ \ chi_1 ^ 2 = 10.0 $，P = 0.002），以及个体范围使用监测周期之间存在相关性（相邻监测周期：$ r_s ^ 2 = 0.5-0.7 $，P <0.0001）。这强调了在个人层面上研究范围使用的重要性。