Title : The effect of egg yolk as a natural croprotecant on viability and fertilization rate of giant grouper spermatozoa fourty eight hours after freezing
Abstract:
Epinephelus lanceolatus (Bloch, 1970), is the largest groupers. The distribution of this spesies is throughout the Indo-Pacific region. The status of E. lanceolatus according to the International Union for the Conservation and Nature is vulnerable. There are some factors involved in declining the population of this species in the last 20 years, such as habitat destruction and overfishing. Re-stocking effort of this species has been conducted through aquaculture, at the moment. The obstacle in re-stocking grouper are having long spawning and protogynous hermaphrodites. Cryopreservation method, accordingly can be applied as an alternative way to solve the re-stoking problem. Cryopreservation is cell storage method conducted at low temperature at a certain time. A major factor supporting for success of cryopreservation is cryoprotectant. There are two types of cryoprotectant namely intracellular (permeating) cryoprotectant and extracellular (non-permeating) cryoprotectant. Therefore, the objective of present study is to evaluate the effect of combination glycerol (permeating) and egg yolk (non-permeating) on spermatozoa quality of E. lanceolatus (viability and fertilization rates) for 48 h. One level of glycerol (6%) combined with six levels of egg yolk solution (0%; 5%; 10%; 15%; 20%; and 25%) were tested in this study. Marine fish Ringer’s solution was used as an extender. The diluted sperms were equiliberated for 10 min. at 4ºC, and then kept at -20 ºC for 48 h. Sperm was thawed at 45 ºC for 30— 60 s. Spermatozoa viability and fertilization rates were then evaluated. The one-way ANOVA showed that combination glycerol and egg yolk solution had a significant effect on spermatozoa viability and fertilization rates (P<0.05). The study revealed that the 15% egg yolk solution combined with 6% glycerol resulted in the highest rates of viability (81.44 ± 2.06%), and fertilization rates (77.31 ± 1.90%). Conclusion: A 15% egg yolk solution combined with 6% glycerol in marine fish Ringer’s solution was the best cryoprotectant for E. lanceolatus spermatozoa preserved at -20 ºC for 48 h.Short Description of what will be discussed during the presentation (about 250 - 500 words)
