Effects of storage duration and storage temperature on viability of stored ova of kutum (Rutilus frisii kutum) in ovarian fluid
Effects of post-stripping oocyte ageing and temperature on egg viability rates were studied in kutum (Rutilus frisii kutum). Eggs were retained outside the ovarian cavity (in vitro storage) with ovarian fluid at various temperatures of 4, 10, 12 and 26°C. Stored ova of six female kutum were fertilized separately after 0 (control eggs fertilized prior to storage), 2, 4, 6, and 8 h post-stripping (HPS) using fresh and pooled sperm obtained from five males. Eyeing, hatching and eyed egg mortality rates were recorded as an index of egg viability. The results indicated that the maximum eyeing (87%) and hatching (75%) rates of eggs took place at 0 HPS followed by 8 HPS (> 80 and > 70%, respectively) at 4°C. As storage temperature increased, egg viability decreased to 80, 70 and 50% viable at 8 HPS at 4, 10 and 12°C, respectively. The eggs stored at 26°C lost their viability almost completely after 4 HPS. Eyed-egg mortality increased from 13% at 0 HPS to 48.2% and at 4 HPS, at 26°C. This study demonstrated that the in vitro storage method is an applicable effective fertilization technique that can be used for restocking programs of kutum within 8 h at temperatures ranging from 4 to 12°C.
Key words: Rutilus frisii kutum, egg storage, temperature, ovarian fluid.