Fig. 2
From: Impact of feed, light and access to manipulable material on tail biting in pigs with intact tails
The absolute incidence of tail injuries (presumably caused by tail biting) recorded at slaughter in the herd before the trial (black line). There was a positive correlation (P < 0.0001, generalised linear model test, least square means comparisons) between daily weight gain and tail injuries. The figure also shows the mean incidence of tail injuries in the abattoir where the pigs were slaughtered (blue line) and in Sweden in general (red line) over the years