Effect of dietary fish powder on intestinal flora and development of arthritis in the pig

In 1971 Månsson et al. reported that a 20% dry fish powder diet fed to young pigs induced arthritis and increases in faecal Clostridium perfringens counts. To confirm this interesting finding we have repeated their experiment by following their regimen as closely as possible. Twelve piglets of Finnish landrace were divided at 8 weeks of age into two groups according to litter, sex and initial weight. The control group received a cereal-based diet. In the experimental group 20% of cereal in the diet was replaced by fish meal. Stool samples were cultured for Cl. perfringens and subjected to direct gas-liquid chromatography (GLC) to provide bacterial cellular fatty acid profiles. Development of arthritis was monitored macroscopically, and synovial samples were taken at autopsy for microscopical examination. Faecal Cl. perfringens counts increased 10-40 times more in the fish diet group than in the control group. GLC revealed a significant difference in bacterial florae between the groups. No arthritis was observed and only slight synovial inflammation in four experimental pigs and in one control pig. We conclude that fish diet changed faecal flora significantly, but did not induce arthritis.