Abstract
The present study was carried out in order to explore the effect of different artificial mediums and in vitro storage periods on fertilization, eyeing and hatching success of scaly carp (Cyprinus carpio) eggs. The batches of about 200 pooled eggs treated with 20-ml three different extenders (Ringer, Dettlaff and Cortland) and Ovarian fluid in 15-cm petri dishes, were stored at 22.5⁰C for 30, 60, or 90 min. The in vitro stored eggs were fertilized by adding of 50 μl sperm which showing motility higher than 80%, in each petri dishes end of the storage period. The highest fertilization rates were determined as 86% and 72% with the egg samples stored for 60 min in Cortland solution and for 90 min in Ovarian fluid respectively (p<0.05). The highest eyeing rate (80%) was determined in egg samples kept in Cortland solution for 60 min storage (p<0.05). Despite the best hatching rate (60%) of the egg samples determined with Ovarian fluid at 30 min storage, the Cortland solution was (48%) the best for 90 min (p<0.05). Results indicate that Cortland solution is the most suitable extender and can be substituted instead of Ovarian fluid for in vitro storage of scaly carp eggs.
Highlights
Fertilization, eyeing and hatching of eggs Following 30, 60 and 90 min storage periods of unfertilized eggs, extenders and Ovarian fluids were removed from the petri dishes and 50 μl sperm showing motility higher than 80% and containing roughly 2x105 spz. was added on to the eggs for the fertilization
Regarding the effect of storage periods on fertilization of eggs, the highest results were obtained as 71.33±9.45%, 82.00±4.00% and 68.00±4.00% in Dettlaff and Cortland solutions and Ovarian fluid respectively for 30, 60 and 90 min storage periods (Figure 1)
30 min 60 min 90 min Discussion In spite of cryopreservation of fish sperm developed with a satisfactory level, it has been less successful for the fish eggs due to the difficulty of removing intercellular water during the cooling process
Summary
Conservation of gametes in the cold or frozen state is an important biotechnological tool and has great concern for aquaculture. Growing attention to this biotechnology has guided an increasing number of researches in this field (Carolsfeld et al 2003; Tiersch 2011). The long-term conservation of fish sperm has been widely explored and optimized with cryopreservation techniques. Nowadays, it is possible using cryopreserved sperm in artificial propagation applications in aquaculture. Ovulated eggs retained in the ovarian cavity are exposed to overripening because of morphological and biochemical modifications affecting gamete and fertility quality negatively (Formacion et al 1993). Prolonging of egg viability is an important issue in term of aquaculture practices (Rothbard et al 1996)
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