• Energy Research

Immunocastration, a technique to replace surgical castration of piglets, consists of two consecutive vaccinations to induce antibodies which transiently suppress testicular functions and avoid boar taint. It is a method to ensure both a high product quality and a high level of animal welfare. The impact of immunocastration on the three pillars of sustainability has been studied extensively. While all aspects of sustainability have been studied separately, however, a contemporary global overview of different aspects is missing. In immunocastrates, performance results are better than in barrows, but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows, but higher than with boars. The level of aggression is considerably lower in immunocastrates compared to boars. Societal concerns are mainly related to food safety, and are not supported by scientific evidence. After second vaccination, immunocastrates switch from a boar- to a barrow-like status. Therefore, the timing of second vaccination is a fine-tuning tool to balance advantages of boars with environmental and economic benefits against increased risk of welfare problems and boar taint. Nevertheless, both synergic and conflicting relationships between the pillars of sustainability must be communicated along the value chain to produce tailored pork products.

The impact of pork production on global livestock's greenhouse gas emissions is substantial. Understanding the factors influencing these emissions is crucial in achieving a more sustainable pig husbandry. In two independent experiments, the impact of slaughter weight on the carbon footprint (CFP) of pig feed intake (CFPFI) was evaluated for growing-finishing pigs of different sexes (entire males (EM), barrows (BA), immunocastrates (IC) and gilts (GI)). In experiment 1 118 animals were raised individually in experimental conditions. In experiment 2 384 animals were housed in group (four pigs per pen), in controlled commercial farm circumstances. All animals were fed ad libitum in a three-phase feeding regime and slaughtered at different BW, ranging from 110 to 148 kg (experiment 1) and from 99 to 138 kg (experiment 2). When only the fattening period was considered, the CFPFI was expressed per kg carcass growth. When the production of piglets was also taken into account, the CFPFI was calculated per kg carcass weight. For all sexes, the heavier the pig, the higher the CFPFI per kg carcass growth (P < 0.05, experiment 1; P < 0.001, experiment 2) and per kg carcass weight (P < 0.05, experiment 1; P < 0.01, experiment 2). In addition, BA had a significantly higher CFPFI per kg carcass growth and per kg carcass weight compared to EM and IC and to EM, IC and GI in respectively experiments 1 and 2 (P < 0.001). When performing a desk study with a soy-free (i.e. reduced CFP) feed in the third phase of experiment 2, slaughter weight no longer affected the CFPFI per kg carcass growth (P = 0.133) and per kg carcass weight (P = 0.856). A higher slaughter weight thus implies a lower sustainability, unless a sufficiently low-CFP feed is provided in the finisher phase.