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The value of a good night's sleep:
measuring hens' motivation for night-time perching. Anna Olsson and Linda Keeling Swedish University of Agricultural Sciences, Sweden Operant methods have been increasingly used to address questions of animal welfare. Since good welfare requires that animals are allowed to perform behaviours they are motivated to do, it is important that applied research uses appropriate methods to assess motivation. Presently, the most commonly used approach is operant methodology generating demand curves. However, the interpretation of these relies on the assumption that demand is not affected by the size of the reward and, consequently, such methods are appropriate for commodities of which the size can be varied along a continous scale but less suitable for resources which have a value only if the animal is given full access to them until it has completed the behaviour. Roosting during night-time in hens is one such behaviour. We have used a weighted push-door giving different levels of resistance to test the motivation of laying hens to use perches for roosting, alone or with a companion. The highest resistance passed, as well as several behavioural variables, were used as the measure of motivation. The results indicate that hens were motivated to use a perch for night-time roosting but the additional value of a companion hen could not be established. Keywords: animal welfare, motivation, operant |
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