The potential of feeding patterns to monitor the welfare of growing-finishing pigs

Samenvatting

Feeding patterns, including feed intake and its underlying behaviours (i.e. feeding frequency, duration and rate), may show rapid and extensive deviations from basal levels during welfare challenges. With the use of data from electronic feeding stations and algorithms, feeding patterns may serve as practical, continuous indicators of pig welfare. We systematically reviewed the literature on the relation between feeding patterns and growing-finishing pig welfare, covering both negative and positive welfare states. We found that clear links were described between feed intake and physiological welfare issues such as clinical disease, thermal stress and tail biting wounds. Additional value was found in the behaviours underlying intake, as they show distinct deviations in response to different physiological issues and respond rapidly, allowing for early detection of issues. For behavioural issues, such as abnormal behaviours and feed competition, generally the underlying feeding behaviours deviate and not intake itself. The range of abnormal behaviours studied is however limited, and it could be questioned whether mild forms of feed competition, which could be coped with adequately, can be distinguished from severe forms of competition that lead to welfare issues. On the positive side of welfare, differences in intake and duration have been reported between pigs housed in barren or enriched environments, but the direction of these effects is inconsistent between studies. Studies using animal-based indicators of positive states, such as play or tail postures, are currently absent. We conclude that feeding patterns are a promising tool to continuously monitor pig welfare. Feed intake and its underlying behaviours should be used concomitantly, on a short time scale (i.e. within the day) and using group and individual level simultaneously. We note that the variation in feeding patterns between and potentially within pigs is large, and should be better understood before the welfare-relevant deviations can be accurately interpreted