Motility and energetic status of Atlantic salmon (Salmo salar L.) sperm after refrigerated storage

Sperm storage in the appropriate diluents brings positive results usually assessed at the level of percent of motile sperm and fertilization rate. Occasionally sperm motility parameters were taken into consideration. The aim of this study was to investigate whether dilution in artificial seminal plasma significantly affects energetic status and motility pattern of Atlantic salmon sperm. The sperm from 11 males was stored separately in two modes on ice (+2-+4°C), for 10 h until examined: one part of milt was stored in thin layer of 5-6 mm under air condition, while the other part was diluted at the ratio 1 : 50 in artificial seminal plasma in a sealed tube. Energetic parameters i.e.: ATP, ADP, AMP, GTP, GDP, GMP, IMP, NAD, NADP, adenosine, guanosine, inosine were determined by HPLC. Motility parameters were measured using CASA. Eight sperm motility parameters were analysed: MOT, VCL, VAP, VSL, LIN, STR, ALH and BCF. After storage the concentrations of ATP, TAN and AEC value of the diluted spermatozoa were significantly (P < 0.001, P < 0.01, P < 0.01, respectively) higher (by 35, 22, 10%, respectively) than those of the spermatozoa kept undiluted. Reverse the concentrations of the degradation products of energetic nucleotides (IMP, adenosine, inosine) were significantly (P < 0.01, P < 0.01, P < 0.001, respectively) higher in undiluted control than in those stored in dilution (by 417, 105, 600%, respectively). Higher concentrations of ATP accumulated in the spermatozoa in diluted milt, ensured significantly (P < 0.01) higher velocities (by 13%, VCL) at the beginning of analysis. Moreover, linearity and progressivity of spermatozoa from diluted milt were significantly (P < 0.01) more by 16 and 12%, respectively. The percent of motile spermatozoa and BCF do not differ significantly between variants. The velocity of the spermatozoa stored in dilution, however, dropped much quicker, which caused a significant shortening of the entire motility phase by about 8 s - relative to sptz from the undiluted samples. This shortening of the motility phase was the only negative effect of storage in dilution observed in our study. No correlation was found between ATP and motility parameters measured (P > 0.05). Dilution of salmon milt during short-term storage in artificial seminal plasma is recommended for these species. The technique used in the present study resulted in a significantly better sustenance of the energetic status of spermatozoa and had beneficial effects on the motility parameters at activation such as sperm velocity, linearity and progressivity.