The effect of pen design and the tranquilising drug, azaperone, on the growth and behaviour of weaned pigs.

Two experiments were carried out in a 55-sow, specific pathogen free commercial unit, to assess the effects of the tranquilising drug, azaperone, on pigs mixed at weaning. The drug is claimed to inhibit aggression in pigs mixed at weaning, and also to increase the average weight gain in groups of growing pigs. The first experiment used a single test and control group, and the second experiment was a 2 X 2 factorial design, the variables being the presence or absence of the drug, and the presence or absence of a box used to modify the weaner pen environment. In both experiments there were no significant differences in rates of agonistic interactions between treated and untreated groups, although the drug delayed the first agonistic encounters for about 8 hours. Nor was there any difference in the relative growth rate between treated and untreated groups in either experiment.