[Long-term effects of a deworming program using flubendazole and levamisole on the percentage of condemned livers in slaughtering pigs].

A deworming programme continued over a period of twenty-four months was carried out to study the proportion of livers condemned because of milk spots, which was unacceptably high on a pig-fattening farm in the Province of Limburg, the Netherlands. In order to remove Ascaris suum from the fattening pigs initially present and to prevent subsequent contamination of the houses with worm eggs, three courses of deworming treatment with flubendazole were initiated on the farm. All newly incoming piglets were systematically treated with 2 ml. of 5 per cent levamisole from the beginning of the trial, this treatment being continued from December 1976 to January 1979. A total number of 3,861 animals took part in the trial. Observations in the slaughter-house started within eight months after the first treatment. The proportion of livers condemned wholly or in part had dropped to 3.6 per cent by that time and showed a further decrease to a mean level of 2.4 per cent during the 17-month period of observation. A significant increase of the mean daily growth was observed at the same time. These results were verified by a similar trial on another farm.