Development of a system for automatic measurements of force and visual stance variables for objective lameness detection in sows: SowSIS

Lameness in sows is an important welfare concern as well as a cause of considerable economic loss. In general, lameness in sows is evaluated by visual scoring of the gait. However, visual assessment is a subjective technique with low reproducibility. Therefore, the need arises for more accurate and objective methods to enable correct detection. A detection system, based on force stance variables derived from force plate analysis and visual stance variables derived from image processing was developed: SowSIS (sow stance information system). The transportable device and computer software was tested in a practical environment and was positively evaluated for its practical use and precise measurements. A preliminary study of the force stance variables was performed by comparing measurements of sound sows and sows with lameness in their hind leg. All lame sows were reluctant to bear weight on their lame leg which resulted in a lower weight exerted by the lame hind leg compared to the other legs. This shift in weight was mainly compensated by putting more weight on the contralateral sound hind leg. Sows showed more but shorter kicks (i.e. lifting leg of the ground) with their lame leg compared to the other legs. The results indicated that the developed system SowSIS has very promising potential to support future objective research in lameness in sows.