Effects of different rooting materials on behaviour and welfare of finishing pigs

Provision of rooting material is important to meet the pig`s need for exploration when housed inside. In this experiment we investigated the effects of different types of rooting materials and a weekly rotation in different materials on behaviour and welfare of finishing pigs. We predicted that access to rooting material would lead to more positive and less negative behaviours, and a lower proportion of pigs with bite marks on ears, tail, and body.

During two batches with a total of 360 finishing pigs, with 10 pigs per pen, rooting material was provided twice a day (pellets, peat, straw, hay, weekly rotation of these materials, or controls with sawdust) over 12 weeks. Behaviour was recorded from video in the two most active periods of the day; immediately after material provision, for 60 minutes, with instantaneous scan sampling every 6 min. and 1/0 sampling. Welfare protocol data was collected in weeks 1,2,3 and 12.

Provision of rooting material resulted in more exploration (P < 0.001), play (P < 0.001) and tail wagging (P = 0.010) compared to the control group, except for pellets where exploration level was even lower than controls. Rooting material also led to less tail biting (P = 0.002) and manipulation of pen fittings (P < 0.001) compared to the control group. Straw and rotation of materials resulted in less ear biting (P < 0.001), and straw in fewer observations with the tail hanging down or tucked between the legs (P < 0.001). Aggression was not reduced (P = 0.036), and non-aggressive social contact was lower with rooting materials compared to controls (P = 0.002). Pigs provided with peat, straw, and hay had a lower proportion of bite marks on the tail (P < 0.001), whereas pellets and rotation groups were higher than controls in this respect. All rooting materials except for pellets resulted in a lower proportion of bite marks on the body compared to controls (P = 0.018). Levels of exploration, play, aggression, ear biting, tail curled, wagging and hanging down (P < 0.001), and tail biting (P = 0.052), were all higher in the first weeks of the experiment and declined with increasing age. Groups with a weekly rotation in materials showed the highest level of exploration throughout the experimental period (P < 0.001).

Our results suggest that straw and hay are highly valued as resources for finishing pigs, and material rotation is the most stimulating.