Domestication effects on foraging strategies in pigs ( Sus scrofa)

Abstract

It has been suggested that domestic animals have lost the ability to respond to environmental changes in an adaptive fashion. Others have suggested that during domestication, a shift may have occurred towards less costly foraging strategies. Eight domestic pigs ( Sus scrofa) and eight crossbred pigs (Holland Landrace×Wild boar) were allowed to forage alone in a maze for 30 min on four successive days. The maze contained six gradually depleting food patches and corridors between them. Pigs obtained the food by manipulating the bucket with the snouts. On every second test the cost of moving between patches was increased by inserting 36.5–38.5 cm high wooden barriers between each food patch. Both breeds adapted their foraging pattern to the depletion of the patches and spent shorter time in each patch on successive visits. Domestic pigs spent longer average time in each patch. Both breeds spent longer time in patches when the maze contained barriers. The ingested amount of feed was reduced in both breeds when barriers were introduced. The domestic pigs passed totally a lower number of barriers compared with the crossbred pigs. Both domesticated and crossbred pigs visited fewer patches in the maze with barriers compared with the maze without. Weight of the pigs was not a major factor affecting the results. We conclude that both crossbred pigs and domestic pigs in general responded as expected from optimal foraging theory. Hence, domestic pigs still posses the ability to adapt their foraging behaviour in an adaptive fashion to the prevailing conditions. Crossbred pigs seemed to use a more costly foraging strategy than domestic pigs.