Fertility of cryopreserved common carp (<i>Cyprinus carpio</i>) spermatozoa

The study was aimed at standardization of cryopreservation protocol for the commoncarp, (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 minutethen -4°C to -80°C at a rate of 10°C per minute and finally held for 10 min) was carried out in acomputer-controlled freezer where 0.25 ml straws containing spermatozoa were stored in a liquidnitrogen container at -196°C. Alsever’s solution with ethanol, Alsever’s solution with methanol andegg yolk citrate with DMSO gave better motility (%) in both pre-freeze (93.33±1.05, 90±1.83 and88.33±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. Consideringboth pre-freeze and post-thaw motilities of the common carp spermatozoa, 1:9 was the best ratiofor 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.v28i0.5287Univ. j. zool. Rajshahi Univ. Vol. 28, 2010 pp. 51-55