Effect of feeding regimen on behavior of growing-finishing pigs supplemented or not supplemented with folic acid

The effect of restricted feeding on the frequency of abnormal behaviors and gastric ulcers was investigated in 72 market pigs. Half of the pigs were fed restricted (R) amounts of feed twice a day (0800 and 1600) and received 90 to 95% of the intake recorded for the other half, which were allowed ad libitum (A) access to feed with addition of feed once a day at 0800. In each feeding group, 24 pigs were supplemented with folic acid. The animals were housed in pairs and the behavior of each animal was recorded during 24 h at 18 and 20 wk of age. The results showed that the A group ate more frequently during light hours than the R group at 18 wk, but not at 20 wk. However, the frequency of eating behavior was higher in the R group than in the A group at 20 wk during the 2 h after feed distribution. Feeding regimen had an effect on the frequency of redirected behaviors during the 2 h preceding feed distribution. The percentage of time spent nibbling on the penmate was higher in R than in A pigs at 18 wk, whereas that of rooting on the penmate was higher at 20 wk. Moreover, the proportion of pigs performing redirected behaviors was higher in the R than in the A group at both ages. The overall frequency of gastric ulcers was similar in pigs given the two feeding treatments, but severe ulcers were more frequent in the R than in the A group. Some interactions were also found between feeding regimen and folic acid. At 18 wk, R pigs receiving no folic acid performed more nibbling on the penmate than all other pigs during the 2 h after feed distribution. At 20 wk, the frequency of eating was lower and that of lying higher during the 2 h after feed distribution in A pigs receiving folic acid than in all other pigs. The present results suggest that feed restriction at 90% of the ad libitum intake adversely affected fattening pigs and that supplementation with folic acid had beneficial effects on their behavior.