The practice of rearing pigs outside for part or all of their life has seen a dramatic increase over the last decade with 42% of sows in England now kept outdoors (June 2008 census).
This trend has been largely driven by retailer demand for pork produced under 'higher welfare' systems for example those meeting RSPCA Freedom Food standard, and also by the economic cost of replacing old and deteriorating housing facilities on pig units.
Management, site suitability, climate and genotype are all aspects of outdoor pig keeping that can cause particular health, welfare and environmental problems if not planned carefully. This ultimately can compromise achievement of the five freedoms, a recognised framework for providing acceptable welfare. Stockmen on outdoor units have to be particularly vigilant to maintain high standards under often very difficult working conditions.
Crucial to the success of outdoor pig rearing is the suitability of the farmland designated for such an enterprise. In general low rainfall areas are preferable so outdoor rearing is most common in the south and east of the country. From an animal health point of view, selecting a site that has light, free draining soil is essential to avoid waterlogging or "poaching" in the winter months. Sites containing sharp stones in the soil structure can cause severe foot problems.
Maintaining good biosecurity on outdoor units is challenging. Keeping rats and foxes to a minimum is possible using rodenticides and electric netting. Birds, however, are a constant problem particularly if the unit is sited near landfill or coastal areas where gulls are prevalent. Birds may carry a number of diseases and pathogens including Salmonella which can be passed on via faeces. More recently the escape and establishment of feral wild boar in southern Britain adds additional risks of carrying and introducing diseases to farmed pigs, particularly those kept outside.
It is normal practice to worm outdoor pigs but condemnation of livers with white spot (migrating ascarid larvae) and rarely deaths from lung worm can be problems. Build up of such parasites and also of bacterial problems over time mean that it is necessary to move on to clean land every two years or so.
Maintaining a grass sward during the period of stocking can be effective at reducing nitrate leaching losses and preventing so...
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