Abstract
Lameness and lesions to the skin and claws of sows in group housing are commonly occurring indicators of reduced welfare. Typically, these problems are more common in group housing than in individual housing systems. Group management type (dynamic versus static) and stage of gestation influence the behavior of the animals, which in turn influences the occurrence of these problems. The present study compared prevalence, incidence and mean scores of lameness and skin and claw lesions in static versus dynamic group housed sows at different stages of gestation during three consecutive reproductive cycles. A total of 10 Belgian sow herds were monitored; 5 in which dynamic groups and 5 in which static groups were utilized. All sows were visually assessed for lameness and skin lesions three times per cycle and the claws of the hind limbs were assessed once per cycle. Lameness and claw lesions were assessed using visual analogue scales. Static groups, in comparison with dynamic groups, demonstrated lower lameness scores (P<0.05) and decreased skin lesion prevalence (24.9 vs. 47.3%, P<0.05) at the end of gestation. There was no difference between treatment group regarding claw lesion prevalence with 75.5% of sows demonstrating claw lesions regardless of group management. Prevalences of lameness (22.4 vs. 8.9%, P<0.05) and skin lesions (46.6 vs. 4.4%, P<0.05) were highest during the group-housed phase compared to the individually housed phases. Although the prevalence of lameness and skin lesions did not differ three days after grouping versus at the end of the group-housing phase, their incidence peaked during the first three days after moving from the insemination stalls to the group. In conclusion, the first three days after grouping was the most risky period for lameness incidence, but there was no significant difference between static or dynamic group management.
Highlights
Since January 2013, all sows in the European Union must be group-housed from four weeks after service to one week before parturition (European Directive 2001/88/EC)
Farms were required to have a sow group housing system established for a minimum of 1 year, were not allowed to change group housing system during the study and were within 100 km from the ILVO institute, and there had to be an equal number of farms with dynamic and static group management
For the total duration of the study 55.2% of the sows of the initial experimental groups were removed; 42% of removed animals came from static groups and 58% from dynamic groups
Summary
Since January 2013, all sows in the European Union must be group-housed from four weeks after service to one week before parturition (European Directive 2001/88/EC). Sows experience one bout of mixing, and the associated aggression, at the beginning of gestation. Dynamic groups have more than one breeding group housed in a pen together at the same time This approach uses pen space more efficiently compared to static groups. Sows are exposed to multiple bouts of mixing and the associated aggression throughout gestation every time a new group of sows is introduced. Due to the more frequent mixing bouts in dynamic sow groups, more aggressive behavior and more skin lesions might be expected [2;16,17,18,19]. As soon as the social hierarchy is established, the fighting decreases and aggressive behavior can be kept to a minimum in well managed and well-designed housing systems [8]. The unrest and agonistic behavior associated with such changes result in more skin lesions and locomotion disorders, including claw lesions [15;17]
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