Passive transfer of immunity to trichostrongyle species infections in sheep. Investigations of specificity and limitations of 'transfer factor' activity with Trichostrongylus axei infections.

The ability of transfer factor (TF) preparations to transfer resistance to challenge with Trichostrongylus axei in sheep and to correct partially the immune immaturity of young lambs was confirmed. Non-dialysed TF consistently transferred resistance but dialysed TF frequently failed, perhaps demonstrating a loss of activity during TF preparation procedures. Specificity of transfer was demonstrated when T. axei TF transferred resistance to T. axei challenge but Haemonchus contortus TF failed to do so.