Mammalian pest problems in organic pig farming, preventive measures and control

Summary

Organic pig farming includes having pigs in open fields with relatively close contact to the wild fauna. The risk of transmission of parasites and diseases to the pigs is therefore higher than in traditional pig farming with pigs under strict control in indoor pigsties. Newborn and sucking pigs are also exposed to predators that may cause losses to the farmers.
A general trend in organic farming is to avoid the use of pesticides. There is therefore a need for effective preventive measures and control methods that are acceptable to the organic farmers.
As a first step in a project for developing strategies for pest management in organic pig farming we conducted a questionnaire survey in Denmark. The farmers were asked questions about what they considered problems arising from the natural environment. They were also asked to describe how they offered fodder and water, which types of huts they used etc. The surroundings should be described regarding factors that were thought to influence the natural fauna, such as e.g. distance to quickset hedges, forests, streams and watercourses.
The results of the survey showed that rats and smaller rodents (mice and voles), foxes and hares were the most frequently occurring mammals in the fields with pigs. The farmers considered rats and foxes as causing the most important (pest) problems. Occurrence of rats is reported significantly more frequently in organic pig farming than in traditional pig farming in open fields.
The answers given by the farmers were analysed as to possible relationships between occurrence of / problems with rodents and the practice regarding the pig farming. There was a significant positive correlation between occurrence of rats, smaller rodents and foxes. Use of automatic feeding systems and open water trays, and having stacks of hay and straw in the fields were all factors that were significantly positively correlated with the occurrence of rats and smaller rodents. The occurrence of smaller rodents was negatively correlated with the use of huts with a bottom and huts made of hard materials. Special shelters for the pigs exclusively made of bales of straw did not give a significant positive correlation with occurrence of rodents.
These results indicate factors that are practicable as preventive measures against rodents. The farmers reported traps, shooting, and cats and dogs as the most frequent non-chemical ways of controlling rodents.