Basal serum cortisol concentrations in cattle

Glucocorticoids play an important role in many metabolic pathaways concerne d with development and control and their serum concentrations reflect the o verall balance between synthesis/secretion and elimination/degradation. Thi s paper summarises the results obtained for serum concentrations of cortiso l, the predominant glucocorticoid molecule in calves, bulls and cows of dif ferent breeds and ages. Thus, a total of 484 blood samples taken from 329 b eef or dairy animals was examined using either liquid-phase or solid-phase radioimmunoassay (RIA) procedures. Values obtained with the easier to perfo rm solid-phase RIA tended to be higher than those with the more sensitive l iquid-phase RIA but the difference was not statistically significant. Altho ugh there were large individual variations between animals in most of the s tudies, mean values of the order of 20 nmol/L were observed in all nonstres sful situations, increased values were found around the rime of parturition in cows, and in the abattoir for bulls. Cows exhibiting ketosis tended to have below average serum concentrations of cortisol. Cortisol levels increa sed with age in young cattle kept under extensive conditions.