Impact of Synthetic Androgen on Milt Quality and Semen Preservation of Gilthead Seabream (Sparus aurata).

The use of synthetic hormones for induced breeding of fish has been a long-standing trend. Studies have demonstrated that exogenous administration of synthetic androgens are effective to improve milt quality of male fish. This study aimed to evaluate the impact Testosterone propionate (TP), a synthetic androgen, on the quality of milt and the preservation (short duration) of Gilthead Seabream semen at 4 oC in oxygen and Fish Ringer's medium. Sexually matured male fishes were given intra muscular injection of Testosterone propionate (TP) at a dose of 1.0 mL. Kg-1, and a control group was maintained without hormone injection. After 36 hours, milt was collected and evaluated for sperm motility, density, sperm viability and colour. Semen preserved at 4 oC in oxygen and Fish Ringer's medium was examined for sperm motility (%), motility duration (sec) and viability (%) at 24,48,72,96 and 120 hours. Significant change in colour or pH of the milt was not observed. Milt's consistency changed from being thick to waterier. The hormone injected fish group had an increased level of milt volume and sperm density than the control. Milt stored at 4 oC in oxygen atmosphere showed higher sperm cell quality than that stored in Fish Ringer's medium. The results of this study can be used as a guideline for induced breeding and hatchery production of Gilthead Seabream, S.aurata.