Aerosolized 5 alpha-androst-16-en-3-one reduced agonistic behavior and temporarily improved performance of growing pigs.

Two experiments were conducted to determine the effect of aerosolized 5 alpha-androst-16-en-3-one (androstenone) on pig aggressive and submissive behaviors and on pig performance. In Exp. 1, twenty-four 5-wk-old pigs were randomly regrouped in a two-pig bioassay. A solution of either isopropyl alcohol or .5 mg androstenone in isopropyl alcohol per pig was aerosolized on both pigs in the observation pens. Summarization of video records from the 90-min bioassay showed that pens of pigs aerosolized with androstenone spent 58% less time engaged in aggressive behavior (P less than .05) and 96% less time engaged in submissive behavior (P less than .01). In Exp. 2, a performance trial was conducted with finishing pigs from 57 to 91 kg body weight. Factorially arranged treatments included aerosolized androstenone (.5 mg/pig) or the vehicle isopropyl alcohol and regrouping into uniform body weight blocks or no regrouping. Regrouping depressed average daily feed consumption (P less than .05) and average daily gain (P less than .05) for the first 7 d of the trial. Pigs reveiving the androstenone aerosol had improved average daily gain (P = .01) and gain:feed ratio (P less than .01) for the first 28 d of the trial. Performance of all treated pigs was similar for the entire finishing period. This olfactory stimulant reduced pig agonistic behavior and transiently improved performance of regrouped and non-regrouped finishing pigs.