Experience of a 10-year use of competitive exclusion treatment as part of the Salmonella control programme in Sweden

In Sweden, competitive exclusion (CE) treatment has been used since 1981 as a part of the national control programme for Salmonella. According to the programme all broiler flocks are tested for Salmonella before slaughter thus providing an evaluation of CE treatment. The CE culture used is mainly for the two consecutive flocks raised in a unit after a Salmonella-infected flock has been identified. During the period 1981–1990 CE culture has been given to 179 flocks, involving 3.82 million chickens. Only one of the treated flocks was found to be Salmonella-positive. A special study during a period when Salmonella was spread by contaminated feed demonstrated that CE treatment was effective in controlling Salmonella under field conditions. A likely contributory factor is that the hatcheries in Sweden can be claimed to be Salmonella-free. In addition, the control programme and related action, have led to a very low incidence of Salmonella in broiler chickens. A nationwide study carried out in 1990 demonstrated that less than 1% of broiler chickens was contaminated with Salmonella after slaughter.