Observations on behaviour and skin damage of slaughter pigs and treatment during lairage

In five Dutch and four Belgian slaughterhouses the following elements were studied: (1) slaughterhouse husbandry practice, (2) agonistic behaviour in groups of pigs, (3) indices of skin damage following slaughter recorded on a relative scale of 1-4 where 4 indicates severe damage. Variation in slaughterhouse husbandry practice was considerable (stocking density range, 1.0-3.1 pigs m(-2); range of time spent in lairage prior to slaughter, 0-3 h). Brooms and/or electric goads were used to move pigs in all slaughterhouses and in one Dutch abattoir handling with sticks seemed to contribute considerably to skin damage. The level of agonistic behaviour was lowest during the first 10 min in lairage. In the Dutch slaughterhouses, large individual differences in aggression between pigs were observed. Pigs in Belgian slaughterhouses were tranquillized prior to transport, resulting in generally low levels of agonistic behaviour. The percentage of resting animals increased steadily up to an average of 36% in the Dutch abattoirs and 45% in the Belgian abattoirs after 1.5 h. In both the Dutch and the Belgian slaughterhouses, skin damage was higher in the front (2.3 +/- 0.1 and 2.1 +/- 0.3, respectively) and in the middle region (2.2 +/- 0.2 and 2.1 +/- 0.2, respectively) than in the hind region (1.7 +/- 0,1 and 1.4 +/- 0.2, respectively) of the pig. For the Dutch slaughterhouses, skin damage was significantly associated with time kept in lairage (P < 0.05) and with stocking density (P < 0.05). It is suggested that to decrease aggression and skin damage and thus to increase welfare in the Dutch slaughterhouses visited, stocking density should be lower and pigs should be slaughtered as soon as possible after arrival.