Influence of an exogenous androgen, testosterone propionate on milt quality and short-term preservation of milt of Asian seabass Lates Calcarifer

 Asian Seabass Lates calcarifer is widely used for pond and cage culture practice in the Kingdom of Saudi Arabia. A studywas carried out to understand the influence of an exogenous androgen, Testosterone propionate (TP) on milt quality ofL. calcarifer. Intramuscular injection of TP at dose 1.0 ml kg-1 was given to mature male fishes grown in a brood stockpond. A control was also maintained without giving hormone injection. After 36 h of injection, milt was collected and miltquality was assessed for colour, sperm cell concentration, motility and viability of spermatozoa. Short-term preservation ofmilt was carried out in oxygen and marine teleost Ringer’s medium at 4oC for 120 h. No significant change was observedin colour and pH of milt, but nature of milt changed from thick to watery due to hormone injection. Enhanced milt volume(14%) and sperm cell concentration (4%) was noticed in fishes from the treatment group 36 h post-injection, when comparedto control. Sperm motility duration and percentage motility were high in treatment fishes than control. Milt preserved inoxygen medium showed high sperm motility and viability when compared to Ringer’s medium. Intramuscular injection ofTP at 1.0 ml kg-1 improved milt volume and quality and therefore can be used for induced breeding of Asian Seabass. Keywords: Asian Seabass, Hormone, Intramuscular injection, Milt quality, Ringer’s medium, Sperm motility, Testosteronepropionate