Effect of Dexamethasone on Gonadotropin Secretion in Postpartum Anestrous Range Cows

Story in Brief An extended interval from calving to first estrus in beef cattle may be associated with environmental stress and, suckling which increase the secretion of adrenocorticotropic hormone (ACT H) by the pituitary gland. Increased secretion of ACTH causes greater amounts of corticoids to be secreted by the adrenal gland. This experiment was designed to determine if treatment of anestrous cows with dexamethasone, a synthetic corticoid, would inhibit the release of ACTH by the pituitary and, as a result, alter secretion of the luteinizing hormone (LH) and alter the interval from calving to estrus. Treatment with dexamethasone did not influence the percentage of cows in estrus by 85 days after calving, however, it tended to lengthen the interval from calving to first estrus in those cows that exhibited estrus. The. pattern of LH secretion was altered for several days after treatment.