Influence of immunisation against GnRF on agonistic and mounting behaviour, serum testosterone concentration and body weight in male pigs compared with boars and barrows

The aim of the present study was to assess the effects of vaccination against boar taint on testosterone levels, body weight and behaviour in male fattening pigs when compared with boars and barrows. The study was carried out in two replicates over time. Pigs were allocated to fattening pens according to treatment group (immunised males (IM), castrated males (CM), entire males (EM)) with 10 and 13 pigs per pen in batches one and two, respectively. IM pigs were vaccinated twice with Improvac™ according to manufacturer's instructions (first injection was given on the day of entry to the fattening unit, second injection was performed when pigs had an average weight of 76.6 kg and 80.4 kg in the two replicates over time, respectively). During fattening, pigs were videotaped twice (test periods one and two) for a consecutive period of 96 h during each test period and blood samples were taken. Live weight measurements were conducted on a weekly basis. Before second vaccination was given (test period one), IM pigs had serum testosterone levels comparable to those of entire boars. Two weeks after second Improvac™-injection (test period two) testosterone levels of IM pigs decreased significantly ( p p p