Relationships between fat and plasma androstenone and plasma testosterone in fatty and lean young boars following castration.

The effect of weight of fatty tissue on fat and plasma androstenone and on plasma testosterone relationships was studied in the young boar following castration. For this purpose, 9 boars were castrated at 175 days of age, plasma steroid levels were determined daily up to 10 days after orchidectomy and fat androstenone concentration was measured 1, 3, 6, 10 and 15 days after castration. The results show that the apparent half-life of stored androstenone is very variable between boars (range: 4 to 14 days) and do not depend on the weight of fatty tissue. The rate of elimination of plasma androstenone is also very variable between boars. The rate of disappearance of fat androstenone following castration does not depend on the rate of androstenone release from fatty tissue to peripheral plasma but is more likely dependent on the intensity of plasma androstenone catabolism and elimination. Therefore, fat androstenone concentration in the intact boar is almost only depending on the equilibrium between the respective rates of testicular production and elimination.