Development of Milt Cryopreservation Protocol for Economically Important Minor Carp Cirrhinus reba (Hamilton, 1822)

Abstract

Background: Reba carp is one of the promising candidates for species diversification in fresh-water aquaculture. It is available in all the major rivers of India. Cryopreserved milt will be useful in genetic exchange between remotely located farms. For using cryomilt as a tool for genetic exchange, species specific milt cryopreservation protocol is required. Methods: Milt was cryopreserved using three extenders (7,7B and 9C) and two cryoprotectants (DMSO and methanol) and evaluated with fresh milt as control. Milt was cryopreserved in 1:6 dilution in French medium straws of 0.5 ml. The feasibility of selected extender and cryoprotectant combinations was assessed by the ability of cryopreserved sperm to fertilize the C. reba eggs and hatching percentage. Fertilized eggs were incubated in 0.5 L bowl and a flow-through incubation system. Analysis was done for both bowl and flow-through incubation separately and combinedly as well. Result: Better hatching percentage was obtained in flow-through incubation system for all the treatments. In combined analysis extender 7 with 10% DMSO as cryoprotectant gave significantly higher hatching rate (44.5%) and (75%) in comparison to control. Better performance was noticed in flow-through incubation system (50.09%) as compared to bowl (39.1%) in the same treatment. Thus, it can be concluded that extender 7 with 10% DMSO (V/V) is suitable to retain sperm quality in reba carp having optimal sperm motility, high fertility and hatching close to the values obtained with fresh sperm in flow-through incubation system.