In vitro maturation of Nile tilapia (Oreochromis niloticus) testicular spermatozoa in different media considering with motility, oxidative stress, fatty acid profile and fertilization capacity.

Collection and usage of testicular spermatozoa are often required for reproduction practices due to low sperm volume, reduced sperm density, urine contamination, and utilization of spermatozoa of sex-reversed broodstocks. No previous study has investigated in vitro maturation (IVM) of Nile tilapia (Oreochromis niloticus) testicular spermatozoa, despite being a widely cultured species in the world. The main aim of the present study was to establish an IVM protocol for testicular spermatozoa of this species. Accordingly, testicular sperm samples were first diluted with four different media including Leibovitz L15 Medium (LE15), and monitored in terms of their motility parameters at 4 and 28 °C. After determination of the optimum medium (as LE15) and the most appropriate temperature condition (as the first 3 h at 28 °C and followed by incubation at 4 °C), the changes in oxidative condition as well as fertilization and hatching rates were determined. Motility parameters, oxidative status and fatty acid profiles of the testicular spermatozoa improved with this IVM protocol compared with those from fresh and undiluted testicular spermatozoa. Fertilization and hatching rates were found as 92 % and 75 % with stripped spermatozoa, 58 % and 47 % with fresh testicular spermatozoa, 17 % and 11 % for undiluted testicular spermatozoa, 76 % and 63 % for in vitro matured spermatozoa, respectively. The results of the study provide useful information on the usage of testicular spermatozoa for propagation in Nile tilapia.