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Spatial Ecology of Free-ranging Domestic Pigs in Western Kenya

03 April 2013

Following a first study of the natural ranging behaviour of free-range pigs, researchers say that the wide areas covered by the animals has important implications for the control of porcine and zoonotic diseases.

In a paper in BMC Veterinary Research, Lian F. Thomas and colleagues at the University of Edinburgh in Scotland and the International Livestock Research Institute in Nairobi, Kenya, report that in many parts of the developing world, pigs are kept under low-input systems where they roam freely to scavenge food. These systems allow poor farmers the opportunity to enter into livestock keeping without large capital investments. This, combined with a growing demand for pork, especially in urban areas, has led to an increase in the number of small-holder farmers keeping free-range pigs as a commercial enterprise.

Despite the benefits which pig production can bring to a household, keeping pigs under a free-range system increases the risk of the pig acquiring diseases, either production-limiting or zoonotic in nature.

This study used Global Positioning System (GPS) technology to track free-range domestic pigs in rural western Kenya, in order to understand their movement patterns and interactions with elements of the peri-domestic environment.

The researchers found that these pigs travel an average of 4,340 metres in a 12-hour period and had a mean home range of 10,343 square metres (range: 2,937 to 32,759 square metres) within which the core utilisation distribution was found to be 964 square metres (range: 246 to 3,289 square metres) with pigs spending on average 47 per cent of their time outside their homestead of origin.

These are the first data available on the home range of domestic pigs kept under a free-range system, concluded Thomas and colleagues. Their data show that pigs in these systems spend much of their time scavenging outside their homesteads, suggesting that these pigs may be exposed to infectious agents over a wide area.

Control policies for diseases such as Taenia solium, Trypanosomiasis, Trichinellosis, Toxoplasmosis or African Swine Fever, therefore, require a community-wide focus and pig farmers require education on the inherent risks of keeping pigs under a free-range system.

The work presented here will enable future research to incorporate movement data into studies of disease transmission, for example for the understanding of transmission of African Swine Fever between individuals, or in relation to the life-cycle of parasites including T.solium.


Thomas L.F., W.A. de Glanville, E.A. Cook and E.M. Fèvre. 2013. The spatial ecology of free-ranging domestic pigs (Sus scrofa) in western Kenya. BMC Veterinary Research. 9:46. doi:10.1186/1746-6148-9-46

Further Reading

You can view the full report (as a provisional PDF) by clicking here.

April 2013

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