Application of a practical method for short-term stored common carp sperm with extenders and quality adjustment before fertilization for breeding success

The main objective of this study was to elucidate whether there are any effects of sperm dilution time before short-term storage in common carp. The sperm of five males (2-2.5 kg body weight, 3 years old) with good spermatozoa motility (>90 %) were diluted with carp extender immediately, 3 h post-diluted, and undiluted fresh sperm was used as control. Sperm motility and velocity of undiluted and diluted sperm were evaluated using a CASA system. A two-way ANOVA revealed that spermatozoa motility, curvilinear velocity (VCL), and straight-line velocity (VSL) were significantly impacted by storage time, varying dilution with extenders, and their interaction (p < 0.001). Sperm motility and velocity dropped steadily with increasing storage periods for diluted sperm, while they drastically fell for undiluted sperm and became immotile at 5 days poststorage. In the control group, the mean percentage of sperm motility was achieved by 40.60 % at 3 days post-storage and sperm diluted with Cejko solution immediately and 3 h post-diluted sperm retained motility at 65.13 % and 65.63 %, respectively, at 3 days post-storage and retained motility of 39.45 and 40.43 %, respectively, at 7 days post-storage. After 7 days poststorage, the diluted (immediately and 3 h post-diluted) pooled sperm had a 61.01 % and 56.70 % fertilization and a 43.40 % and 36.52 % hatching rate, whereas fresh sperm had an 89.34 % fertilization and 78.06 % hatching success. According to the results of the fertilization and hatching assay, compared to fresh sperm, 7 days of stored diluted pooled sperm produced a 68.29 % fertilization rate and a 55.60 % hatching rate.