Normal behaviour as a basis for animal welfare assessment

It is generally agreed that farm animal welfare is at a high level when the animals can behave naturally. Most of today's housing systems, however, differ considerably from the natural environment in which the behavioural organisation of the ancestors of our form animal species evolved. Consequently, normal behaviour may be impaired in several ways. Frequency, duration or sequence of behavioural elements may be affected. Some normal behaviour patterns may not occur at all. The animals may also possibly behave in unnatural ways - in patterns that would never occur in nature. Furthermore, it is usual for farm animals to exhibit behaviour which is normal in form, but which is elicited by artificial structures within their housing system. In view of these possible changes in normal behaviour, it is necessary to assess, for each farm animal species and each housing system, whether animal welfare is at risk in any way if the behaviour observed differs from the behaviour that would occur in a natural environment. In some cases the question can be answered by taking a theoretical evolutionary approach. In most cases, however, detailed knowledge about the behavioural organisation of the animals is necessary. Such knowledge is built up from animal motivation studies and investigations into the effect of environmental structures on animal behaviour. A specific problem of on-farm animal welfare assessment is that there is often not enough time to collect sufficient data to make a judgement about the occurrence of normal behaviour. Resource-based assessment methods are appropriate as an alternative, provided that the resource standards used are based on evidence stemming from research into animal behaviour and motivation.