Effect of adrenal stimulation

Brunner, Donaldson & Hansel (1969) showed that ACTH suppressed corpus luteum formation when administered during Days 2 to 8 of the bovine oestrous cycle. We found that adrenal suppression by betamethasone treatment from Day 10 increased the length of the bovine oestrous cycle: plasma concentrations of oestradiol and androstenedione were unaltered but testosterone levels were reduced by 13 % (Kanchev, Dobson, Ward & Fitzpatrick, 1976). The present experiment was undertaken to investigate the effect on plasma steroids ofadrenal stimulation achieved by a synthetic adrenocorticotrophin (ACTH). Five Friesian heifers, 36 months old, were given an intramuscular injection of 2 mg Synacthen Depot (Ciba) equivalent to 200 i.u. ACTH. They were bled by jugular venepuncture before and 2, 6 and 24 h after injection. Plasma was stored at —15°C until analysed. Progesterone and testosterone