Klein T, Zeltner E, Huber-Eicher B
Abteilung Sozial- und Nutztierethologie, Zoologisches Institut, Universität Bern, Ethologische Station Hasli, Wohlenstr. 50a, CH-3032, Hinterkappelen, Switzerland
Appl Anim Behav Sci. 2000 Dec 1;70(2):143-155. doi: 10.1016/s0168-1591(00)00147-7.
Feather pecking is a behavioural disorder in laying hens which consists of pecking the feathers of conspecifics, causing feather damage or even injuries to the skin. Its development can be explained by redirection of foraging behaviour. While the occurrence of feather pecking strongly depends on the kind of housing condition, it is also known that there are strain differences in the tendency to feather peck. From the inverse relation between feather pecking and foraging behaviour found earlier, we hypothesised that genetically determined differences in foraging behaviour could be responsible for the observed differences in feather pecking between strains.In a first experiment we tested whether there are differences in the foraging behaviour of two hybrids. As hybrids, we used Lohman selected leghorn (LSL) and Dekalb; eight groups of 20 1-day old chicks each. They were kept in enriched pens (265cmx90cm) with a litter area (200cmx90cm) consisting of wood-shavings, chaff, straw, polystyrene blocks, sand area (65cmx90cm) and elevated perches. Behavioural observations were carried out in week 4. In a subsequent experiment with the same birds we tested how the foraging behaviour of the two hybrids differed when housing conditions were changed from enriched to restricted and to what extent they developed feather pecking. A 2x2 factorial design with hybrid (LSL, Dekalb) and housing condition (restricted, enriched) as factors and with four replicates of each factor combination was used. Half of the pens of each hybrid were changed from enriched to restricted housing conditions by covering the litter area with slats. Behavioural observations were carried out in weeks 5 and 6.In experiment 1, LSL and Dekalb spent the same amount of time foraging, but Dekalb spent significantly more of that time with pecking and hacking at the polystyrene blocks. On the other hand, LSL spent significantly more time at the feeding troughs and rested significantly less than Dekalb. In the restricted environment of experiment 2, again, the total foraging time did not differ between hybrids, but LSL chicks spent significantly less time scratching, while Dekalb spent significantly more time moving. Both hybrids developed feather pecking but LSL showed significantly higher rates than Dekalb.Our results demonstrate genetic differences in the foraging behaviour and in the way hybrids cope with the change in housing condition from enriched to an environment that is restricted in relation to foraging possibilities. We conclude that the results support the hypothesis put forward that genetic differences in foraging behaviour could be the basis for the genetic influence in the development of feather pecking.
啄羽是蛋鸡的一种行为障碍，表现为啄同类的羽毛，导致羽毛受损甚至皮肤受伤。其发展可以用觅食行为的转移来解释。虽然啄羽的发生很大程度上取决于饲养条件，但也已知在啄羽倾向方面存在品系差异。根据先前发现的啄羽与觅食行为之间的反比关系，我们推测觅食行为的基因决定差异可能是品系间观察到的啄羽差异的原因。
在第一个实验中，我们测试了两个杂交品种在觅食行为上是否存在差异。作为杂交品种，我们使用了罗曼精选来航鸡（LSL）和迪卡布；每组8个，共20只1日龄雏鸡。它们饲养在丰富环境的鸡舍（265厘米×90厘米）中，垫料区（200厘米×90厘米）由木屑、谷壳、稻草、聚苯乙烯块组成，沙地面积（65厘米×90厘米）和高架栖木。在第4周进行行为观察。在随后对同一批鸡的实验中，我们测试了将饲养条件从丰富环境改为限制环境时，两个杂交品种的觅食行为有何不同，以及它们啄羽行为的发展程度。采用了一个2×2析因设计，以杂交品种（LSL、迪卡布）和饲养条件（限制、丰富）作为因素，每个因素组合有4个重复。每个杂交品种的一半鸡舍通过用板条覆盖垫料区，从丰富环境改为限制环境。在第5周和第6周进行行为观察。
在实验1中，LSL和迪卡布花费相同的时间觅食，但迪卡布花费更多时间啄咬和啃咬聚苯乙烯块。另一方面，LSL在食槽处花费的时间显著更多，休息时间比迪卡布显著更少。在实验2的限制环境中，同样，杂交品种之间的总觅食时间没有差异，但LSL雏鸡抓挠的时间显著更少，而迪卡布移动的时间显著更多。两个杂交品种都出现了啄羽行为，但LSL的发生率显著高于迪卡布。
我们的结果表明，在觅食行为以及杂交品种应对从丰富环境到觅食可能性受限环境的饲养条件变化的方式上存在基因差异。我们得出结论，这些结果支持了所提出的假设，即觅食行为的基因差异可能是啄羽发展中基因影响的基础。
