[Pros and cons of anthelmintic treatment of lambing ewes].

The advantages, prevention of gastro-intestinal worm infections in lambs, the improvement in the condition of the ewes during lactation, and the disadvantages, the costs, a possible interference with the build-up of immunity and the risks of the occurrence of anthelmintic resistance are discussed. It is concluded that the advantages more than counterbalance the disadvantages. Providing that the dosage of anthelmintics is correct, that is to say that an overdosage is preferable to too low a dosage, and safe pastures are used, post-lambing anthelmintic treatment of ewes is an effective procedure in preventing gastro-intestinal infections in lambs. Moreover, treatment will eventually improve the condition of the ewes so that, for instance, as the result of a slightly higher milk yield, the gain in weight of the lambs will be promoted.