The serum cortisol levels were highest in serum from
recumbent cows (96.7 nmol/l) and cows suffering from
parturient paresis (78.0 nmol/l) in the present study. Both
these groups had significantly higher (p < 0.001) levels of cortisol than the rest of the cows and most of the cows in
both these groups were close to parturition. Glucocorticoids
also interfere with the absorption of Ca from the
gastrointestinal tract [19]. The hypothesis that cows suffering
from stress and/or painful diseases have elevated
blood glucose levels due to an increase in serum cortisol
could not be verified, as only cows suffering from paralysis
(hypocalcaemia, group PP, and recumbent cows,
group R) showed high blood glucose and serum cortisol
concentrations compared to the others. The cows with
hypocalcaemia (group PP) also had low concentrations of
insulin despite the fact their levels of glucose were significantly
higher than normal, indicating that they were
unable to secrete insulin. This may be a result of the
hypocalcaemia as insulin is secreted by a Ca-dependent
exocytosis. After treatment with calcium solution the
insulin levels were significantly (p < 0.02) increased
(Table 3).