Effects of disturbance on spatial memory in pigs: implications for choice testing techniques

Choice tests, which measure animals' preferences for resources, are increasingly used to aid the design of new husbandry systems. However, under farm conditions, these systems are not always used as desired. A possible explanation for this is that laboratory testing and on-farm conditions induce different states of stress or disturbance in animals which, in turn, affect processes underlying their choice behaviour. One important process which underlies choice behaviour is spatial memory. To choose accurately, animals need to learn and remember the location of different resources. Studies of deer and cattle, which involve animals learning the location of different stimuli, have shown that some individuals are unable to learn to avoid apparently aversive restraining crushes (Pollard et al., 1994; Grandin et al., 1994), and that calmer individuals may make more accurate choices (Grandin et al., 1994).