Significance of serum pepsinogen and abomasal pH levels in a field infection of O circumcincta in lambs.

Serum pepsinogen estimations from serially bled lambs grazing on pasture from spring to autumn showed correlations with the availability of Ostertagia larvae on pasture, with faecal egg counts of O circumcincta, and with Ostertagia worm counts in similar lambs slaughtered fort-nightly from the same pasture. In the slaughtered lambs correlations were recorded between worm count, serum pepsinogen level and abomasal pH. The value of serum pepsinogen estimations as a diagnostic test is discussed with reference to these findings.