Post-mortem spermatophore and sperm cryopreservation of the white shrimp Litopenaeus schmitti

Abstract

This study was carried out in two phases; the first, to evaluate the viability of two cooling protocols (A and B) using glycerol (10%) as a cryoprotectant, and the second, the efficiency of two cryoprotectants (10% glycerol and DMSO) and times (30, 60 and 90 days of storage in liquid nitrogen) for the cryopreservation of post-mortem sperm mass and spermatophores of the shrimp Litopenaeus schmitti. The protocol A presented a cooling rate of 0.5°C min^-1 until reaching -32°C and protocol B, 20°C min^-1 until reaching -120°C, after which the samples were transferred to liquid nitrogen (N₂L). The sperm viability was assessed by smearing the semen stained with eosine-nigrosine. The curve that resulted in higher mean sperm survival was of Protocol A (50.9%). Therefore, for the second experiment, the protocol A was used, however there was no difference between the cryoprotectants for sperm mass, although the influence on survival time. Difference was observed between the cryoprotectants and the influence of time on sperm survival of cryopreserved spermatophores. Glycerol 10% was more efficient for cryopreservation of spermatophore, but for the masses sperm both can be used.