Optimizing Storage Conditions for Kutum (RUTILUS FRISII KUTUM) Ova: Effects of Duration and Temperature

Abstract

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.