[The prophylactic effect of albendazole containing a pulse-release bolus on gastrointestinal helminth infection in calves].

The prophylactic effect of an albendazole containing 'pulse release' bolus on gastrointestinal helminth infection in calves during their first grazing season was tested on a farm in the Netherlands in 1986. Thirty calves were divided into two groups of young calves and two of old calves. On being turned out to grass, calves of one of these groups were given a bolus containing 3 x 2 grammes of albendazole, to be released after thirty-one, sixty-two and ninety-three days. The treated young calves showed a much lower egg-output, produced a lower infestation of herbage, displayed significantly lower pepsinogen levels and showed a significantly better gain in weight compared with the untreated young calves. Differences were not observed between the two groups of older calves, probably because of the fact that one of the treated calves had lost the bolus at an earlier stage.