Production of Worm-free Lambs at Pasture

Abstract

RECENT research has shown that a considerable loss of productivity occurs in sheep carrying a sub-clinical infestation of nematodes parasitic in the alimentary tract^1,2. This work has depended upon comparisons of worm-free and lightly infected groups of animals and has therefore been carried out in indoor pens. It has been concluded that infected sheep gain weight at less than their optimum rate; but it is not clear how valid these results are for sheep at pasture, under normal conditions of continual reinfection by grazing. In order to measure the actual loss due to sub-clinical parasitism it is necessary to compare normally infected sheep with similar, worm-free animals under grazing conditions. An investigation was therefore carried out during March–July 1954 at the Grassland Research Station, Stratfordon-Avon, into the possibility of raising worm-free lambs at pasture.