Effects of Amperozide on Biting Behavior and Performance in Restricted-Fed Pigs Following Regrouping

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Abstract
Eight experiments were conducted to determine the effect of a single administration of amperozide on agonistic behavior and growth performance in newly mixed, restricted-fed pigs. Two hundred 12-wk-old pigs were used in a 4-wk trial (Exp. 1) to investigate the effect of amperozide on agonistic behavior and performance. The pigs were assigned to each pen on the basis of body weight and sex, ensuring that pigs in each pen were unacquainted. Each pig was weighed individually on d 3, 7 and 28. Agonistic behavior was quantified by counting bite and slash marks on each pig at 8, 26 and 48 h after penning. An i.m. injection of amperozide immediately before mixing the pigs reduced the physical damage (P < .001) at each time point. There was no evidence of amperozide causing either sedation or motor disturbances. On the average, amperozide treatment improved (P < .001) daily gain in the 4-wk study period by 70 g (17%). In Exp. 2 to 8, 1,648 pigs growing from approximately 20 to 100 kg body weight were used to determine the effect of amperozide on weight gain. Pigs were penned in groups of 9 to 11, randomly assigned to each pen on the basis of sex. Each pig was weighed individually after penning, on d 35 and at slaughter. Untreated control pigs had a poorer growth performance than did amperozide-treated pigs. During the first 5 wk postpenning average daily gain was improved (P < .001) by 90 g (26%) in pigs receiving a single oral administration of amperozide at penning. For the entire growing-finishing period daily gain was improved (P < .05) by 20 g (3.2%). Amperozide treatment did not affect daily gain in restricted-fed, acquainted pigs (Exp. 9). The results indicate that treatment with amperozide is an effective way to minimize the negative growth effects of agonistic behavior and the concomitant social stress following regrouping. Copyright © 1988. American Society of Animal Science . Copyright 1988 by American Society of Animal Science