5α-ANDROSTENONE IN PERIPHERAL PLASMA OF PIGS, DIURNAL VARIATION IN BOARS, EFFECTS OF INTRAVENOUS HCG ADMINISTRATION AND CASTRATION

Abstract

ABSTRACT 5α-Androstenone2) has been measured in pig peripheral plasma by radioimmunoassay (RIA). In 73 mature boars values ranging from 1.2 ng to 54.1 ng per ml plasma with a mean value of 18.3 ng/ml and sd = 15.9 were found. In female pigs and castrated male pigs the mean concentrations were 2.3 ng/ml (n=18) and 1.1 ng/ml (n=19) with sd = 0.8 and sd = 0.3 respectively. Clear-cut diurnal variations in the concentration of 5α-androstenone in plasma samples from boars were not observed. Intravenous injection of HCG in boars caused an abrupt rise in the 5αandrostenone level reaching a maximum in 90 min. Twenty-eight hours after the injection a second peak of plasma 5α-androstenone was observed. Following castration of boars the level of 5α-androstenone in peripheral plasma fell within 4 days, to levels found in female pigs.