Evaluation of the effect of umbilical hernias on play behaviors in growing pigs.

Umbilical hernias (UH) are common in pigs and are an animal welfare concern. This study used an assessment of play behavior to evaluate the welfare of pigs with UH. Twenty-one grower pigs with UH and 17 without hernias (WUH) were assigned to 16 playing groups (PG) of 2 or 3 pigs (with at least 1 UH pig per PG). The time each animal was engaged in any of the defined playing behaviors for locomotor/social or toy play behaviors was recorded. Mixed Poisson or negative binomial and linear models were used to determine the effect of UH and day of session, accounting for the cluster of pigs within groups, on the frequency of each play behavior, and playing times. Pigs with UH had the same frequency of most play behaviors and playing times as pigs without hernias. There was no indication that the presence of UH-affected play behavior or performance in pigs.