In conventional pig production, pigs are often kept in
groups of up to 20 and space allowance is generally low. In
alternative deep litter housing systems, with very large
group sizes and increased space allowance, lower levels of
nosing and pushing pen mates and increased locomotor
activity have been found (e.g. Morrison et al., 2003).
However, studies of variations in space allowance in
conventional pens are few. Provision of rooting materials
has been found to reduce aggression (Schaefer et al., 1990),
and has been suggested to affect aggression and abnormal
behaviour more than space allowance (Beattie et al.,
1996). However, space allowance may be important for
pigs’ use of rooting material. For instance, immediately
after allocation of fresh material, competition for access
may be enhanced by limited space and available space may
affect pigs’ opportunity to interact with the rooting
material provided, especially as the pigs approach slaughter
weight.