Agonistic behaviour, skin lesions and activity pattern of entire male, female and castrated male finishing pigs

Fattening of intact boars is the least invasive alternative to the detrimental welfare effects of surgical castration of piglets. However, beside problems such as boar taint the divergent agonistic and sexual behaviour of boars may impair the pigs’ welfare during fattening. To evaluate the effect of sex on agonistic interactions a total of 108 female, 108 castrated male and 108 entire male German crossbred pigs with an initial average body weight of 25 kg were kept in nine pens during three replicates with 12 pigs per pen respectively (1.2 m2 per pig) separated by sex. Pigs were slaughthered at about 115 kg body weight. Agonistic behaviour was recorded 24 h before and 24 h after, and skin lesion scores (from 0 to 3) were recorded four days before and three days after half of the pigs have been removed in each pen for slaugthering. In addition, the daily activity pattern of groups was examined by a motion sensor system during 72 h before removing half of the pigs of a group. The frequency of mounting, knocking and fighting was significantly higher in entire males both before and after removing half of the pigs from groups. Disturbance of social structure by removing half of the pigs per group did not affect the total number of agonistic interactions in any sex. Entire males showed a higher incidence of skin lesions at the neck and the ham before, and at the shoulder after half of the pigs were removed for slaughtering. However, the severest lesion score 3 was not found in any group and for score 2 the highest incidence of 3.7% was found at the shoulder of entire males after removing half of the pigs per group. The activity pattern of the pigs was not affected by sex. It was concluded that under housing conditions used in the present study (ad libitum feeding and low stocking density) fattening of entire male pigs can be done without severe detrimental effects on their welfare.