Metyrapone and adrenal response in stressed calves

The effects on some hematochemical stress indices of previously administered metyrapone (750 mg given orally six times every 4 hours) were evaluated in calves submitted to simulated transport for 30 min. The plasma cortisol increases were significantly lower than those observed in untreated calves of the same age, sex and breed. Plasma adrenaline and NEFA increased similarly in both groups of calves during simulated transport and were unaffected by metyrapone administration. The results indicate that in cattle, as in other animals, metyrapone inhibits cortisol biosynthesis. Under our experimental conditions, the rise of NEFA, a well known stress index, seems mainly to be related to adrenaline release.