Preliminary results using metabolites and in vitro grown larvae of Ostertagia circumcincta to immunise lambs against oral challenge.

An attempt was made to immunise lambs by the intra-muscular injection of concentrated metabolites obtained from the in vitro culture of Ostertagia circumcincta, by the oral administration of lyophilised metabolites or by the subcutaneous injection of living third, fourth and fifth stage worms grown in vitro. Protection appeared to have been elicited by each treatment as the worm burdens, the lengths of the worms and the faecal worm egg counts in the immunised lambs were less than those of the control lambs.