Clean grazing systems for sheep have been developed to minimize helminth challenge to susceptible lambs. Provision of clean grazing relies upon effective control of overwintering helminth infection on pasture and particularly in the post parturient ewe. During early lactation ewes immuno-competence is reduced resulting in the excretion of helminth eggs for approximately six weeks post lambing (Thomas, 1973). Control of this source of infection may be achieved by strategic anthelmintic administration while overwintering pasture infection may be avoided by use of pasture which has not carried sheep in the previous year.

Prophylactic anthelmintic administration is unacceptable under an organic management system and consequently alternative strategies must be sought to eliminate the ewe as a source of infection. The objective of the present study was to evaluate strategic transfer of ewes and lambs to a silage aftermath as a means of minimizing helminth challenge to susceptible lambs.