Implications of food patch distribution on social foraging in domestic pigs (Sus scrofa)

Abstract

Feeding behaviour of social animals can be influenced by the spatial distribution of resources. In domestic housing facilities growing pigs will often be fed from feeding sites confined to a small area, i.e. effectively a clumping of food resources. In the present experiment we investigated how feeding behaviour of growing pigs changed with increasing distance between feeding sites. During 20-min feeding tests, eight groups, each consisting of four growing pigs (35.4±2.7kg), were allowed to eat from four buckets containing food pellets placed in a test arena in a rectangular pattern. The positions of the buckets, determined by their mutual distance, were close (15–25cm), medium (245–290cm) or far (460cm). Feeding behaviour of the pigs was video recorded. There was a significant effect of feeding site position on all variables investigated except for the number of displacements from food buckets (i.e. time spent eating, intake, number of bouts, mean bout duration, number of aggressive interactions, number of shifts to new feeding sites: P<0.0001; mean duration of aggressive interactions: P=0.0010; displacements: P=0.3228). Physical separation of food sites (medium and far) affected aggressive interactions (lower frequency, longer mean duration) compared to minimal separation (close). Time spent eating, number of feeding bouts, number of shifts to a new site, and food intake decreased with increasing distance between food sites (from close to far). Mean bout duration was affected by physical separation of, but not distance between, feeding sites. These results indicate that feeding behaviour is markedly different when resources are clumped and even a small separation of troughs can profoundly alter patterns of aggressive behaviour and feeding.