The effect of post-natal environmental enrichment on tail biting in growing pigs

Redirected explorative behaviour has been proposed as a contributing factor to tail biting in pigs. We hypothesized that providing material for oral manipulation from birth to weaning reduces oral manipulation of other piglets and later tail-biting. We allocated 59 sows and their litters to two treatments in a matched-pairs design. Farrowing pens in the control treatment (n=29) had enrichment representing the minimum required by Finnish legislation: wood shavings twice a day and one suspended plastic ball. Farrowing pens in the enriched treatment (n=30) had the same plus newspaper (non-glossy, partially made of recycled pulp) twice daily and 10 suspended sisal ropes. All piglets were undocked. The piglets were weaned during week 4, and two litters were combined in each growing pen, all of which had the same level of enrichment. Targets and frequencies of oral manipulation were recorded on video during weeks 2, 3, and 9. Tail damage was scored during week 9. Weaning weight and age did not differ between the treatment groups. Oral manipulation of pen-mates differed between treatments: in control pens, the mean numbers of manipulations/piglet/minute were 0.83 and 0.82 at weeks 2 and 3 respectively; in enriched pens, the means were 0.60 and 0.56 at weeks 2 and 3 respectively (P < 0.001, repeated-measures ANOVA, PASW 18). At week 9, no significant difference was found in the observed behaviour parameters. The prevalence of tail damage of the worst category 4 (part of tail missing) was 8.6% in the control treatment and 0.9% in the enriched treatment (P < 0.001, Fisher’s exact, Statistix 9). The prevalence of category 3 (wounds with inflammation) was 23.5% in the control treatment and 8.8 % in the enriched treatment (P < 0.001, G-test, Statistix 9). It is concluded that additional enrichment in early life has promising implications for reducing tail biting.