ENDOCRINE EFFECTS OF A SINGLE INFECTION WITH OSTERTAGIA-OSTERTAGI IN THE CALF

Abstract Endocrine effects of a single dose of 100,000 infective Ostertagia ostertagi larvae in the calf were investigated. Changes in hormone levels reflecting digestive, thyroid, adrenal and pituitary function were monitored using radioimmunoassay techniques previously validated for use in cattle. A significant increase in pepsinogen and gastrin was recorded in infected calves reflecting changes in abomasal function. A decrease in insulin levels was also demonstrated following Ostertagia infection and may have been related to changes in protein metabolism. A depression in total thyroxine levels, reversed by anthelmintic treatment, was apparently associated with reduced feed intake and therefore seen in both infected and pair-fed control animals. The metabolic effects of this change were, however, unlikely to be marked since free (or unbound) thyroxine remained unaltered. A small drop in growth hormone levels in the infected group was also noted.