Relationship Between Rooting Behaviour and Foraging in Growing Pigs
The objective of the present study was to investigate the relationship between rooting behaviour and foraging in growing pigs. In study 1, forty-eight 11-week-old pigs were housed in eight groups of six with access to a rooting substrate in the form of spent mushroom compost. In half
of the groups the rooting substrate contained food rewards, and in the other half of the groups it did not. All pigs had ad libitum access to feed. In study 2, one hundred and ninety-two 11-week-old pigs were housed in thirty-two groups of six, all with access to spent mushroom compost,
and eight groups were each fed to 70, 80, 90 or 100% appetite. Treatments were applied over a two-week period in both studies. The number of pigs involved in active rooting (rooting in substrate while standing), inactive rooting (rooting in substrate while sitting or lying) or non-rooting
activity (standing in substrate area and involved in any activity except rooting) was recorded by scan sampling. These behaviours tended to reach a peak in the morning and again in the afternoon. Inactive rooting was not significantly affected by treatments in study 1 or study 2. Food rewards
in the rooting substrate led to a significant reduction in active rooting behaviour and in non-rooting activity during peak periods of the day (P < 0.05). It is suggested that learned associations between rooting behaviour and acquisition of food caused the pigs to stop rooting when all
the food rewards had been consumed. The fact that rooting was performed in the absence of nutritive feedback suggests that this behaviour is performed independently of its appetitive foraging junction. Restricting feed levels to 70 or 80% of appetite led to a significant increase in active
rooting and in non-rooting activity during peak periods (P < 0.05). The relationship between feed restriction and active rooting behaviour tended to be linear (P < 0.08). This suggests that levels of rooting behaviour are flexible in response to nutritional needs.