1. Introduction
Housing with fully perforated floors is commonly used for early-weaned pigs, since this encourages the physical separation of the pig and its dung, and allows increased
stocking density. However, the behavioural and other disadvantages of this type of Ž
. housing are well documented for example, van Putten and Dammers, 1976 . Bedded
housing systems may redress the behavioural problems but can encourage enteric Ž
. problems for example, Silver, 1989 , and have other practical management disadvan-
tages such as increased labour requirement. The Straw-Flow
w
housing system was developed to provide the welfare advantages of straw without the associated manage-
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ment disadvantages Bruce, 1990 , and was shown to be successful in this for
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growingrfinishing pigs by Lyons et al. 1995 . In evaluating a new housing system for its effects on animal welfare, many factors
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must be taken into consideration. Broom 1989
stated that ‘‘The welfare of an individual is its state as regards its attempts to cope with its environment’’. Welfare can
therefore be assessed by measuring the extent of coping strategies, one form of which involve behavioural modification. Abnormal behaviour is not necessarily a sign of
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suffering Dawkins, 1980 , and should be interpreted with caution. However, a compari- son of behaviour in different environments can provide indications of modified patterns,
and identify whether one system leads to the performance of more potentially harmful behaviours than another. The built environment may lead directly to abnormal be-
haviours, for example by restricting movement, or providing slippery floors which may
Ž lead to abnormal methods of lying and rising, and a reluctance to change posture Fraser
. and Broom, 1990 . It may also give rise indirectly to abnormal behaviour by failing to
provide adequate circumstances for appropriate expression of highly motivated be- haviours. Thus, changes in activity patterns, pen-directed behaviours and pig-directed
behaviours may be indicative of housing inadequacy. Such behavioural assessment should then be combined with assessment of other welfare parameters to arrive at an
overall conclusion. This paper describes a behavioural investigation into the suitability of Straw-Flow for early-weaned pigs, when compared with systems chosen to reflect the
range of other housing in curent commercial use. The long-term effects of weaner housing are also considered, since residual influences of the early housing environment
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have previously been reported in pigs for example, Boe, 1993 . Other, nonbehavioural Ž
. Ž
. aspects of the investigation are described by Kelly et al. 1998 , and Kelly et al. 2000 .
2. Materials and methods
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