Feeder use patterns in group-housed pregnant sows fed with an unprotected electronic sow feeder (Fitmix).

Previous studies on feeder use in group-housed pregnant sows focused on dynamic groups and protected electronic sow feeders (ESF). This study observed 60 pregnant sows, 1st to 8th parity--housed from Day 29 of pregnancy to 1 week before parturition in stable groups of 20 animals, 1 Fitmix feeder per group. Data from 25 nonconsecutive 24-hr feeding cycles showed sows making several visits to the feeder. Literature on conventional ESF indicated shorter daily feeder occupation. Daily feeder occupation per sow decreased over time (p < .001). The study observed maximum feeder activity in the hours following the start of each feeding cycle. During the experiment, there was a relatively stable, quickly established, and maintained feeder order (W > 0.80, p < .001). This highly correlated with dominance rank (r(s) = 0.80, p < .001). High-ranking sows fed earlier and made as many--but longer--visits as low-ranking sows; thus, they occupied the feeder more time every day (p < .01). Although optimization of the feeder efficiency may take several weeks, Fitmix seems an efficient feeding system for medium-size, stable groups of sows.