The effects of immuno- and surgical-castration on the behaviour and consequently growth of group-housed, male finisher pigs

Abstract

An experiment was conducted to compare behaviour, in particular social and feeding behaviour, and consequently growth performance of group-housed entire and castrated male pigs during the finisher stage of production. Three treatments: (1) entire males, (2) immuno-castrated males, treated with Improvac ® at 14 and 18 weeks of age, and (3) surgically-castrated males, castrated at 14-days old, were compared to assess whether castration affected feeding and social behaviours. Twelve groups of 15 male pigs were formed at 14 weeks of age (47.1±5.50 kg). Pigs had ad libitum access to pelleted, commercial feed from two single space feeders per pen. Pig behaviour and feeder utilisation were compared during 24-h periods at 17 and 21 weeks of age, using time-lapse video recording. At 17 weeks, entire males and immuno-castrated males were more active ( P<0.05) than surgical-castrated males (21.9, 19.8 and 16.1% of 24 h), but at 21 weeks there were no differences among the treatments (pooled mean 16.4% of 24 h). As expected, social behaviour at 17 weeks was greater ( P<0.01) for entire males and immuno-castrated than surgical-castrated males (3.8, 1.8 and 0.1% of 24 h), but not at 21 weeks, when it was greater ( P<0.01) for entire males than immuno- and surgical-castrated males (1.8, 0.5 and 0.4% of 24 h). While the mean time pigs spent in the feeders at 17 weeks did not differ among the treatments (100 min/pig/24 h), at 21 weeks entire males spent less time ( P<0.05) in the feeders (76 min/pig/24 h) than immuno- and surgical-castrated males (110 and 107 min, respectively). On both the observation occasions, the “sexually-active” treatments (entire males and immuno-castrated males at 17 weeks and entire males at 21 weeks of age) on average allocated about one-third of active time to feeding, whereas castrated males spent almost one-half of active time in the feeder, assumed to represent feeding behaviour ( P<0.05). At 23 weeks, there was a trend for entire males to be lighter ( P=0.061) than immuno-castrated males, with surgical-castrated males in between (102.3, 108.9 and 103.9 kg). Thus, castration reduced social behaviour and increased feeding behaviour in group-housed finisher pigs. The results of the experiment also suggest that the social and feeding behaviours of immuno-castrated males at 21 weeks were similar to surgically-castrated males.