Feeding behaviour and performance in relation to injurious tail biting in boars - a longitudinal study

Automatically collected feeder data may be used to predict tail biting in finisher pigs.

Pen-level feeding behaviour and growth were investigated in relation to injurious tail biting (ITB), defined as visible wounds, from 10 weeks before to 4 weeks after the first ITB case in the pen. The data set included 36 pens of 10-12 intact boars between 43 and 148 kg, with average pen weight at ITB onset between 78 and 137 kg. A tail biting pen (TBPEN) had at least one case of ITB, whereas a control pen (CTR) had none. Individual feeding-related data including consumed feed, bout length and -frequency were collected by a single automatic ad libitum feeder. Time (week) relative to ITB onset was referred to as RELWEEK. The time before (PRE-ITB, RELWEEK -10 to 0, n=13 TBPEN and 23 CTR pens) and after ITB onset (POST-ITB, RELWEEK 0 to 4, n=9 TBPEN and 21 CTR) were analysed separately. Effects of TBPEN (vs CTR), bodyweight and RELWEEK were analysed using a linear mixed model with RELWEEK as repeated and pen as random effect.

PRE-ITB the number of predicted feeder visits was lower in TBPEN as compared to CTR and decreased with age (PRED = -18 to -39% at RELWEEK -10 to 0; TBPEN effect p=0.02), leading to a tendency for a shorter daily time in the feeder (TBPEN effect p=0.06). TBPEN showed a growth dip to a -11% PRED level in RELWEEK -9 (TBPEN x RELWEEK p=0.001).

Feeding behaviour changed in TBPEN in RELWEEK -2 to 0. Significant TBPEN x RELWEEK –interactions (p≤0.02) indicated that the relative decrease in the number of feeding bouts accelerated. Together with a progressive shortening of the average feeding bout this led to decreasing relative feed intake and growth (PRED= -10%, -7% and -8% at RELWEEK 0, respectively).

POST-ITB TBPEN still spent less time in the feeder than CTR (TBPEN p=0.04), whereas the difference in the number of visits was decreasing (TBPEN x RELWEEK p< 0.001). There was a tendency for a higher intake per second (TBPEN p=0.08) and a significantly faster RELWEEK-related increase in intake per visit (TBPEN x RELWEEK p< 0.05), as well as increasingly faster growth (PRED= +9% at RELWEEK 4, TBPEN p=0.02) in TBPEN as compared to CTR. The amount of feed consumed did not differ.

Changes in feeding behaviour in TBPEN 10 weeks before ITB suggests presence of some tail-biting related factor. A growth dip 9 weeks before ITB may indicate the involvement of health problems in tail biting. Rapid changes in feeding behaviour suggest that tail biting behaviour begins or escalates 2 weeks before the first tail wounds are detected. TBPEN shows compensatory growth unrelated to feed intake in the month after ITB onset.

Disclosure of Interest: None Declared.