The economic and welfare impact of lameness in sows in England

Aims and objectives:

Lameness in sows is widely accepted as an animal welfare issue yet actual measurement of the impact of lameness on the welfare of the sow is difficult.

A study by Kilbride et al (2008) in 2003-04 found the prevalence of foot lesions in sows in the UK to be 71%. No indication of how many of these animals were lame was given, however, Anil et al (2007) demonstrated that sows with foot lesions were more likely to become lame than those without. Schutter! (2008) collected data from surveys conducted in Australia, Germany, Netherlands and USA and although scoring methods were different between studies, prevalence of lesions was greater than 90% (Australia and USA) and 80% Germany. No actual prevalence for Netherlands was given although  lesion prevalence by type was similar to that in other countries. In a further study by Schutter! (2008) the economic impact oflameness in sows was discussed. Using a model developed by a Dutch network group (Netwerkgroep Perfecte Zeugenklauw) Schutter! calculated the cost /sow in the herd varied from €9.79 in a herd with a low level of lameness to €29.33 in a herd with a high level of lameness and concluded lameness was a costly disorder. The model was based on the costs of replacement and euthanased animals, particularly young animals, medication costs, impact on litter growth/m011ality and labour costs. No other reproductive parameters were taken into consideration.

Following lactation, during which time the majority of sows are in restricted housing, sows in the EU would be moved into group accommodation. Within days of weaning, sows usually return to oestms and will be mounted by other sows in the group and then, if natural service is employed on the fa1m, mounted by a boar(s). It would be expected that the increased exercise demand of group housing together with normal mounting behaviour would be a negative stressor for lame pigs or those with foot lesions. The impact of lameness/foot lesions during this period on subsequent reproductive performance has largely been ignored, yet stress during this period is known to significantly impact reproductive performance.

Housing conditions in the UK for sows is varied and includes indoor and outdoor systems, solid and slatted/pai1ially slatted floors and with differing amounts and type of bedding. Kilbride et al (2008) concluded that to protect against injury, outdoor housing or a solid floor with deep bedding were optimal systems, however the study looked at all ages of pigs from pre-weaning pigs to sows and there were substantial differences between age groups. To our knowledge, no cost benefit analysis of changing housing system on the impact of lameness in the UK has been conducted given the cun-ent legal housing requirements for sows.

To enable the industry to give informed advice on the impact of lameness on the welfare of sows and their productivity, these parameters need to be scientifically assessed. Any recommendations on housing systems should also provide a cost benefit analysis.

Summary of findings:

Lameness in pigs is a major welfare concern and one of the most commonly reported reasons to premature culling of breeding sows. The prevalence of lameness in sows was estimated from 113 English pig breeding units and different risk factors associated with the occurrence of lameness were examined, followed by an assessment of the economic costs of lameness in sows. The prevalence of lameness in sows was 4.3%, and at least one lame sow was observed at 50.4 % of the 113 farms. In both indoor and outdoor sows, the presence of a prevention plan for lameness at the farm significantly affected the occurrence of lameness. Farms with higher producing sows were more likely to have a prevalence of lameness of 5% or higher. When only indoor sows were considered, the odds of lameness occurring at the farm increased with the number of sows in the pen. Lameness was also more likely to occur at farms where sows were housed on solid flooring than when they were kept on slatted or partly slatted flooring. Depending on the severity of the case, the estimated cost of an initial case of lameness could range from £19 to above £266. An increased awareness of the risk factors behind lameness is essential in farm management and can be useful when designing housing areas as well as developing future prevention plans for lameness.