Investigating the development of piglet feeding behaviour during the immediate postweaning phase using computer vision.

Adequate feed intake is a crucial factor driving piglet health during the weaning transition, and therefore, this study investigated the feeding behaviour in the immediate postweaning period under varying conditions of preweaning socialisation and feed familiarity in a 2 × 2 factorial design. During the first 3 days postweaning, 288 weaned piglets (21.8 days old), housed in 24 pens (n = 6 per treatment) with 12 piglets per pen, were video recorded. Preweaning socialisation involved co-mingling piglets from three litters 10 days before weaning and maintaining these groups after weaning, whereas conventionally reared piglets from three litters were mixed at weaning. Feed familiarity involved providing piglets with supplemental creep feed in an additional feeder after weaning, which was identical to the conditions during the final days before weaning. In contrast, the dry feeder and the weaner diet were unfamiliar to the animals. It was hypothesised that both co-mingling and feed familiarity would promote early postweaning feeding behaviour. To assess feeding behaviour, two image classification models were trained to process the video recordings and predict time spent at each feeder. The models achieved a precision and recall of 0.93 for the dry feeder and 0.91 for the creep feeder. To further explore the behavioural dynamics, including aggression and group hierarchy formation, it was hypothesised that co-mingling would reduce aggressive interactions during the immediate postweaning phase. An aggression detection model was developed using classical motion detection techniques combined with skin lesion scoring as a validation metric. The aggression detector achieved a precision of 0.96 and a recall of 0.71 on a balanced test video. A bi-harmonic circadian feeding pattern was identified, and piglets demonstrated group feeding behaviour shortly after weaning. Co-mingling increased the time spent eating creep feed on day (d) 0 and d1 (P < 0.019) and reduced aggression during the same period (P < 0.016). Providing additional creep feed increased the total time spent eating on d0 (P = 0.001) but decreased time spent eating weaner feed on d1 and d2 (P < 0.001). Moreover, increased total feeding time during the first 12-36 h postweaning correlated positively with cumulative feed intake over a longer period (d0-14). To conclude, both preweaning co-mingling and feed familiarity stimulated early postweaning feeding behaviour, while co-mingling also reduced aggression. Feeding behaviour during the immediate postweaning phase appears crucial for promoting adequate feed intake throughout the entire weaning transition.