Up until a few years ago, according Mark White's report for NADIS BPEX, 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 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.

The report suggests that mortality rates on farm may have increased over recent years because of the additional pressures associated with higher sow productivity, the risk of prosecution for allowing the transportation of unfit animals and a shortage of resources to treat sick animals on farm.

Comparing sow mortality rates on farms with different levels of productivity, it appears there is a weak direct relationship in that sow mortality rate rose from around 3.5 per cent where annual output is under 22 pigs per sow to about 5.0 per cent for those achieving 24 to 26 pigs per sow per year. However, the most productive farms (with an output of more than 26 pigs per sow per year) had a sow mortality averaging only just over 3 per cent.

Annual sow mortality rate is linked to farm output (pigs per sow per year)

Monthly mortality averaged about 4.5 per cent and was consistent throughout the year. There is no sign of the spikes in mortality observed in the US as the result of PRRS, the report says.

Analysing sow mortality related to housing system raised some interesting trends. The rate in indoor systems is double that of sows kept outdoors, and losses with slatted floor systems (at 5.4 per cent) is markedly higher than with straw-based systems (4.3 per cent). This was not surprising for, as the report points out, 'Leg problems have previously been identified as a major cause of loss in some herds, contributing 50 to 70 per cent of all deaths (usually by euthanasia)'.

One clear trend that emerged from the survey was that sow mortality is directly related to herd size: the rate for herds of of over 700 sows was 3.5 times higher than for those herds with up to 100 sows. The report suggests this might be related to the greater amount of individual care possible on smaller farms.

The report concludes, '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.'

Further Reading

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You can view the full report by clicking here.