Free Range Hens Tagged with Trovan Microchips
There is growing demand by consumers for eggs produced by birds housed in non-cage systems with the majority of non-cage eggs in the UK being produced using free range systems. The common feature of all free range systems is that they allow birds to have continuous daytime access to outdoor runs which are ideally covered with vegetation and which are subject to stocking density restrictions. Consumer perception is that these systems are of higher welfare as birds are able to perform their normal repertoire of behaviors such as pecking, scratching and dust bathing in a more natural environment on the range. While access to the outdoor range is assumed to be of great benefit, the modern hen, after spending 20 weeks inside during rearing and early placement before the pop holes are opened, has been reported as being disinclined to range outside. From a welfare perspective the birds are depriving themselves of being able to engage in a range of natural behaviors which might result in a redirection of behaviors associated with aggression and feather pecking. Feather pecking is a behavior problem that occurs most frequently amongst domestic hens reared for egg production. It occurs when one bird repeatedly pecks at the feathers of another. In severe feather pecking, the feathers of the recipient are grasped, pulled at and sometimes removed. This is painful for the receiving bird and can lead to trauma of the skin or bleeding, which in turn can lead to cannibalism and death. Although it is known that increased flock ranging is associated with reduced risk of feather pecking, there is little information to explain the reluctance to range outside. The purpose of this study was to address the fundamental question of what proportion of a commercial flock uses the pop holes, how frequently do they use the pop-hole, and how this distribution changes during the lifetime of the flock and under different weather conditions. The hens were implanted with ID-100 Trovan transponders and their movements detected using customized readers built into each pop hole. The findings concluded that a significant proportion of the flock accesses the pop holes on a regular basis with only a very small proportion preferring to stay in the house. There was an effect on age of the birds, time of day and daily mean temperature on pop hole usage. Additional factors included wind speed, rainfall and hours of sunshine.
