The report outlines the problems caused by housing entire males in commercial units, including aggression caused by competition over social dominance and feed as well as injury caused by sexual behaviour. It considers some of the options for reducing prevalence of these problem in order for entire male pigs to reach their potential of higher and leaner growth rates than females and castrates.
The Entire Male Pig Production: Welfare Management Issues highlights a range of possible solutions to tackle welfare issues caused by entire males in commercial units. Measures include selection of genetic lines with reduced aggressive tendencies, modification of housing environment to reduce the level of social contact, provision of manipulable materials which allow natural rooting behaviour and temporary reduction of testosterone in male pigs through an Improvac® welfare management programme.
The report was produced by agriculture and science consultancy Food Animal Initiative (FAI), and commissioned by Pfizer.
The report’s author Ruth Clements said: “Rearing entire male pigs can give producers an advantage in terms of a potential growth rate advantage, and obliterates the need for painful castration procedures for the pigs. However rearing entire male pigs can present its own challenges which can leave producers unable to capitalise on any growth rate potential, and leave pigs exposed to other welfare problems resulting from aggressive and sexual behaviours.”
The report said that rearing entire male pigs in modern commercial systems could result in increased levels of aggressive, sexual and social behaviours for all pigs in the pens by leading to a range of unwanted behaviours, with aggressive behaviour increased during the mixing and moving of animals. It said: “Where normal behaviour is carried out at an increased frequency and becomes problematic, this is often a result of increased social and body contact with other pigs, a lack of environmental enrichment such as manipulable materials and high competition for resources such as food and water.”
Studies have indicated that increased aggression is stimulated by testicular steroid hormones, and that these behaviours stimulate an increase in plasma testosterone, forming a positive feedback level between hormone levels and aggressive and sexual behaviour.
Improvac is a vaccine produced by Pfizer which is used as alternative to physical castration to reduce boar taint caused by androstenone. It creates a temporary immune response in the boar, producing antibodies which neutralise gonadotrophin releasing factor and blocking the mechanism that controls testicular function.