NADIS BPEX Commentary – January 2009

Up until a few years ago the main focus of concern over sow wastage was premature culling – often as a result of leg weakness or poor reproductive performance. A number of factors have altered in recent times to place more emphasis on sow deaths on farms which of course includes a significant number of animals euthanased either directly on welfare grounds or due to a lack of facility for the local slaughter of animals where there is uncertainty over whether they are suitable for transportation. In the current climate of welfare in transport concerns, many stockmen will elect to destroy a sow on the farm rather than risk prosecution for the transport of an unfit animal. It may well also be true that productivity demands have increased in specific herds putting a greater strain on the sow, especially when young, leading to leg problems requiring euthanasia. Pressures on space, staff and the low individual value of the sow will also tend to favour rapid destruction rather than prolonged treatment.

Anecdotal comments from NADIS reporting veterinary surgeons in England and Wales certainly suggest an association between high productivity and high sow mortality in individual farms. Graph 1 shows this trend to some extent but the highest producing herds of all have lower mortality.

Quantitative data collected by NADIS reporters’ highlights a number of other factors. Average sow mortality through 2008 measured on a 3 month rolling average (Graph 2) is remarkably consistent suggesting that losses are system related and constant rather than due to any sudden changes or disease challenges. (The US strain of PRRS can cause sudden spikes of mortality in sows and its absence in the UK is reflected in the long-term mortality picture).

Leg problems have previously been identified as a major cause of loss in some herds contributing 50-70 per cent of all deaths (usually by euthanasia). It is therefore perhaps not surprising that mortality levels in indoor systems are double those of sows outdoors and losses on slatted based system exceed those on straw (5.4 per cent v 4.3 per cent) (Graph 3). Furthermore, the previously identified differences in system types between the 2 major pig keeping areas monitored – NE England favours indoors and to some extent slats whilst East Anglia has a preponderance of straw based and outdoor farms – is reflected in sow mortality being double in the NE compared to East Anglia (Graph 4).

Finally, Graph 5 highlights the rising death rates as herds get larger with the largest herds (those containing more than 700 sows) reporting mortality levels 3.5 times that of the smaller herds of less than 100 sows – an observation which is consistent with the expectation that the smaller producer may have more time and facility for caring for the compromised sow and be able to effect a cure on some of their animals thus avoiding the need for euthanasia.

The cost of sow mortality to the industry is substantial; lost production (dependant of stage of the cycle in which death occurs), premature loss of young breeding animals, loss of cull value and cost of disposal, add to the welfare issue of dead sows to render this aspect of pig farming worthy of greater attention.