Fertility of cryopreserved common carp ( Cyprinus carpio ) spermatozoa

The study was aimed at standardization of cryopreservation protocol for the common carp, ( Cyprinus carpio ) spermatozoa for using in the artificial propagation. Three extenders (Alsever’s solution, egg-yolk citrate and 0.9% NaCl) were combined with three cryoprotectants (ethanol, methanol and DMSO). Two-step freezing protocol (5°C to -4°C at a rate of 4°C per minute then -4°C to -80°C at a rate of 10°C per minute and finally held for 10 min) was carried out in a computer-controlled freezer where 0.25 ml straws containing spermatozoa were stored in a liquid nitrogen container at -196°C. Alsever’s solution with ethanol, Alsever’s solution with methanol and egg yolk citrate with DMSO gave better motility (%) in both pre-freeze (93.33±1.05, 90±1.83 and 88.33±2.11, respectively) and post-thaw (80±4.28, 74.17±3.96 and 76.67±4.59, respectively) periods whereas, 10% cryoprotectant gave the best motility during post-thaw period. Considering both pre-freeze and post-thaw motilities of the common carp spermatozoa, 1:9 was the best ratio for the milt and cryodiluents. The egg yolk citrate with DMSO yielded the best fertilization (37.67±1.76%) and hatching (28.67±1.85%) compared to other combinations under study. Key words: Cyprinus carpio ; spermatozoa; cryopreservation; cryoprotectant; cryodiluent; fertility. DOI: 10.3329/ujzru.v28i0.5287 Univ. j. zool. Rajshahi Univ. Vol. 28, 2010 pp. 51-55