Twenty-four hour changes in androgens, cortisol and prolactin concentrations in primitive Asiatic pigs

Twenty-four h changes in plasma concentrations of cortisol, prolactin and a ndrogens in both sexes of primitive Asiatic pigs (Vietnamese - Sits scrofa vittatus) were investigated. Blood samples were drawn from indwelling femor al artery catheters and plasma concentrations of hormones were analysed by radioimmunoassay. All three investigated hormones showed statistically significant 24 h chang es in boars with higher levels in the morning (cortisol, prolactin, and and rogens) and in the early (prolactin) or late (cortisol) evening. Patterns o f plasma cortisol and prolactin concentrations in gilts were the same as in boars, whereas androgen concentrations in gilts were not changed. The boar s' androgens showed 24 h changes but without a consistent circadian rhythm. Only plasma cortisol concentrations in boars as well as in gills had a circ adian rhythm with the following cosine curve characteristics for boars and gills, respectively: acrophases (point of 24 h with maximal hormone value) 9.24+/-5.23 h, 7.37+/-3.06 h; amplitudes 1.70+/-1.07, 2.25+/-1.67 ng/ml and 24 h means 9.20+/-0.72 and 7.05+/-0.68 ng/ml.