Trials with Phenothiazine-Salt Mixtures for the Prevention of Parasitic Gastritis in Lambs

Abstract

Summary Experiments are described in which comparison of weight gains, worm egg counts and pasture larval estimations respectively were made in groups of lambs ( a ) treated with phenothiazine, ( b ) allowed access to phenothiazine-salt mixtures, ( c ) untreated controls. The trials were carried out in weaned hill lambs on second year grass in autumn and winter, and in suckling lambs running with their mothers on first year grass (1944) and second year grass (1945). In all cases it was found that the use of phenothiazine-salt mixtures caused a depression in worm egg counts. In the 1944 season, i.e. , on first year grass, the level of parasitic infestation remained very low until the post-weaning period, when the phenothiazine groups gained a slight advantage over the controls. In the 1945 experiment the level of parasitic infestation was sufficient to cause loss in condition and in this trial the lambs on phenothiazine-salt showed a significantly greater weight gain than the controls. The same effect was noticed in the group dosed with phenothiazine. On the control plot the pasture larval counts rose to a high level but those on the two phenothiazine plots remained moderately low. It is suggested that phenothiazine-salt mixtures might prove useful in keeping pasture infestations at a low level and thus reducing the amount of dosing required, but it is emphasised that further experiments would have to be done before the method could be generally recommended for use in this country