Degree of competition at feeding differentially affects behavior and performance of group-housed growing-finishing pigs of different relative weights.

The effect of competition at feeding on specific categories of growing-finishing pigs was studied in order to provide an explanation for the increased variation in performance within pens previously seen in highly competitive feeding environments. Individual feed intake and feeding behavior, performance, and health were compared for relatively small, medium, and large pigs in pens of 16. Pens contained either one or two dry feeders during a period of ad libitum eating followed by a period of restricted feeding. Computerized feeders that registered the time and amount of feed consumed by each individual were used. Seven replicate groups on each of the two treatments (a total of 224 pigs) were studied. In the pens with only one feeder, the small pigs ate less (P < 0.05) and tended to have a lower daily weight gain (P < 0.10) than the small pigs in pens with two feeders. However, they had a better feed conversion efficiency (P < 0.05). The small pigs also had a different eating pattern. A considerably larger part of their daily feed intake was consumed during the nighttime hours (P < 0.001) when only one feeder was available rather than two feeders. The large pigs ate more during the restricted period (P < 0.01) and had a lower carcass meat percentage (P < 0.05) in the pens with one feeder. Some differences in feeding behavior between the two levels of competition were seen for all categories of pigs. No difference in health was observed between pigs in the one- and two-feeder pens for any size category of pigs. In conclusion, the inability of the small pigs to get access to feed in combination with overeating by the largest individuals caused the variation in performance seen within pens with a high level of competition at feeding (one feeder for 16 pigs). From a welfare point of view, feeding systems causing a high level of competition may be detrimental when considering all individual pigs in pens, even when it is possible to achieve acceptable production results on average.