The investigation into the efficacy of immunocastration aimed at the prevention of sex odour in boar's meat

Boar taint or meat sex odour, which can be extremely offensive, is frequently present in meat from non-castrated male pigs. This defect is principally caused by sex steroids, primarily androstenone, as well as indole and its derivatives, mainly skatole. Various means have been used to prevent the sex odour in meat, young boar castration being one of the most popular. In Europe surgical castration was most frequently completed without anaesthesia. The procedure is accompanied by pain and stress and conflicts with the principles of animal welfare, which is why it has been abandoned in many countries where animal welfare has been raising growing concern. Thus, it is necessary to produce alternative solutions to prevent this defect in meat. One of the promising alternatives to surgical castration and potential solution to the problem of sex odour in meat, i.e. decline in androstenone and skatole contents in the boar‘s fat, is immunocastration. The main goal of this PhD thesis has been the investigation into the efficacy of immunocastration in the prevention of sex odour in young boar‘s meat. In addition, comparative analyses of carcass muscling and meat quality in castrates, boars and immunocastrated boars have been performed. The acceptability of meat was evaluated by selected trained assessors. The research was conducted on three groups of male animals: surgically castrated pigs (at the age of less than seven days), boars and immunocastrates; each group comprised 30 animals. All pigs were descendents of a single boar (a crossbred of Duroc and Pietrain) and sows of the same line (crossbreds of Landrace and Yorkshire), were kept in identical conditions and fed with the same food. The pigs destined to immunocastration were immunised by s.c. injection of 2x2 ml Improvac vaccine (Pfizer Ltd.). The first dose was administered at the age of eight weeks and the second one five weeks prior to slaughter. The immunogenic material in the vaccine is a synthetic, incomplete analogue of natural gonadotropin-releasing hormone (GnRH) conjugated to a carrier protein. Selected parameters of carcass muscling revealed very similar muscling in immunocastrates to the one in boars, but significantly better in comparison with castrates. Immunocastration resulted in significant, more than 40 %, decrease in testes mass in comparison with the average in boars. Carcass chilling resulted in highest weight loss in boars and lowest in castrates. The pH values in meat measured 60 minutes an