Group composition for fattening entire male pigs underenriched housing conditions - Influences on behaviour,injuries and boar taint compounds

Summary

In organic farming, the production of pork from entire male pigs seems to be the mostpromising alternative to castration, as organic animal husbandry aims at high standards ofanimal welfare and elimination of mutilations. However, previous research on behaviourof entire male pigs was mostly carried out under barren housing conditions and is thus notentirely transferrable to enriched housing conditions. In the present study, we investigatedsingle-sex and mixed-sex groups of entire male pigs and compared them with mixed-sexgroups of castrated male pigs under organic housing conditions. On a commercial farm, 362pigs (average weight 22.7 kg, average age 80 days) were assigned to pens with groups of 20(+1) pigs according to three treatments: single-sex groups with entire males (EE), mixed-sex groups with entire males and females (EF) and mixed-sex groups with castrated malesand females (CF). Skin and tail lesions, lameness and the behaviours ‘head knocking/biting’,‘fighting’ and ‘mounting’ were assessed on five days during the fattening period. Averagecarcass weight for all sexes was 92 kg. After slaughter, female reproductive organs wereinspected for signs of pregnancy. Fat samples of entire male pigs were analysed for concen-trations of androstenone and skatole. Entire males showed more aggressive and mountingbehaviours than castrated males (p < 0.001), and no difference was found between entiremales from the EE and EF treatments. Welfare of female pigs was not impaired when pennedtogether with entire males compared to when penned together with castrates, neither interms of skin lesions nor in terms of received aggressive behaviour. Pigs in the EE treatment had higher lesion scores than those in the EF and CF treatments (p < 0.05 and p < 0.01,respectively), while the two latter treatments did not differ. In the inspected female repro-ductive organs, no pregnancy could be detected. The concentration of androstenone in fatindicated that the presence or absence of females in a group did not have an effect on themale pigs. Of the 177 slaughtered entire male pigs, only one carcass was classified as containing boar taint by a human nose test. Our findings suggest that under enriched housingconditions, entire males can be kept in single–sex groups as well as in mixed-sex groupswith females without compromise in animal welfare.