[The development of weaned piglets experimentally infected with Isospora suis as a model for the effect of lasalocid and halofuginone on coccidia (author's transl)].

Piglets which were early-weaned at the age of 21.7 days and experimentally monoinfected with oocysts of Isospora suis showed distinct reductions in zootechnical criteria during an experimental period of 4 weeks. The daily liveweight gains in the infected piglets (group B) was 19.7% lower than in the control group A, which was free of Coccidia. Comparative photographs with the REM showed serious lesions in the small intestine of infected piglets, which are thought to be mainly responsible for the reduced productivity. The application of 150 mg Lasalocid per kg of total feed to infected piglets caused the rate of weight gain to attain the same values as the noninfected controls (group A). Piglets receiving Lasalocid treatment passed oocysts with the faeces which were infectious. On the other hand, infected piglets which were treated with 6 mg Halofuginone per kg of total feed did not contain any oocysts in the faeces. Despite having a higher liveweight at the beginning of the experiment, this group only gained as much liveweight as the infected piglets (group B). This depression in liveweight gains could be explained by the significantly reduced uptake of feed, which was 21.1% lower than in the controls (group A). 6 weeks after the first infection, a re-infection resulted in the appearance of oocysts in the faeces of the piglets which had been treated with Halofuginone. On the other hand, the animals treated with Lasalocid had developed an efficient immunity to Isospora suis.