Efficient Cryopreservation of Humpback Grouper, Cromileptes altivelis (Valenciennes, 1828) Spermatozoa

Abstract

Chilled storage of humpback grouper, Cromileptes altivelis (Valenciennes, 1828) sperm cells with five extenders was investigated to find the most suitable type of extender for cryopreservation. Five extenders, namely Marine Fish Ringer (MFR), Extender 251 (E 251), Extender 189 (E 189), 0.1 M Sodium Citrate (CT) and 0.9% NaCl (NaCl) were tested. They proved to be appropriate extenders to use since no sperm were motile and all were still alive at 216 h (60 h after chilled storage). There was also no significant difference (p<0.05) in sperm motility when sperm was diluted with extender at 1:1, 1:4 and 1:9. Toxicity to sperm cells was studied with 5 different cryoprotectants i.e. Dimethyl acetamide (DMA), Dimethyl sulfoxide (DMSO), Methanol, Glycerol and Trehalose at 5, 10 and 15% concentrations. The result shows a significant difference (p<0.05) in sperm motility at 5 and 10% of DMA and DMSO; they were the least toxic cryoprotectants. The hatching rates of Humpback grouper eggs from fresh and cryopreserved sperm in 5% DMA and DMSO were high and had no significant difference (p<0.05). [There was no significantly difference (p>0.05) between fresh sperms and sperms cryopreserved in 5% DMSO, but had a significant difference (p<0.05) between fresh sperms and those cryopreserved in 5% DMA.]