THE EFFECTS OF SODIUM PROPIONATE AND ADRENOCORTICOTROPIN ON SERUM CORTISOL-LEVELS IN DAIRY-COWS

The effects of adrenocorticotropin (ATCH) and sodium propionate (Na-P) on cortisol concentrations in the blood serum of cows was examined 10 days after calving. A solution of Na-P (1.84 mol/L) was administered as a single dose (1 ml/kg body weight) intravenously to ten cows, while ACTH was given intramuscularly in a single dose of 25 IU per 100 kg body weight to a further ten cows. A control group of cows received physiological saline solution. Cortisol concentrations were determined 8, 30, 60, 120 and 180 minutes after treatment. It was found that Na-P administration led to a marked increase in serum coristol levels in the examined cows, some animals showing a more marked response than others. The mean maximal increase of nearly seven times the initial value occurred 1 h after administration of Na-P (16.5 +/- 2.2 nmol/l to 11 1.0 +/- 24.5 nmol/L). A similar marked increase in serum cortisol levels was noted after ACTH administration (14.2 +/- 2.5 nmol/L to 126.0 +/- nmol/L), but it occurred after a slight time lag so that the highest serum cortisol concentrations were found after 3h at the and of the experiment. These results show that Na-P has a similar effects on the adrenal cortex as ACTH and its action is very rapid.