A 3-day in vitro storage of rainbow trout (Oncorhynchus mykiss) unfertilised eggs in coelomic fluid at 12øC does not affect developmental success
Le stockage d’œufs non fécondés de truite (Oncorhynchus mykiss) pendant 3 jours dans du liquide cœlomique à 12°C n’affecte pas le développement.
Résumé
Unfertilised rainbow trout (Oncorhynchus mykiss) eggs were stored in vitro in coelomic fluid (CF) and in trout artificial medium (TAM) for 3 and 9 days at 12°C. Eggs held in vivo in the body cavity for 3 and 9 days were obtained from the same females and used as a control. Eggs were fertilised with a pool of sperm obtained from 5 males. The percentage of embryos reaching eyed stage, hatching and yolk-sac resorption, as well as morphological abnormalities were recorded as an index of egg quality (fertility and developmental success). Unfertilised eggs stored 3 days in vitro in CF exhibited the same quality as eggs stored 3 days in vivo (control). After a 9-day storage in CF, egg quality was lower for the 2 females analysed. For eggs held 3 days in TAM, eying, hatching and swim-up rates were significantly lower than in vivo. After 9 days in TAM, fertility and developmental success were extremely low. Unfertilised eggs stored 3 days in vitro in CF and in vivo (control) exhibited the same percentage of morphological abnormalities at yolk-sac resorption. Surprisingly, no malformation was observed at yolk-sac resorption when unfertilised eggs were stored 3 days in vitro in TAM. This study demonstrates that coelomic fluid can be used at 12°C for external storage of trout eggs for at least 3 days without loss of egg quality. In contrast, a 3-day storage at 12°C in trout artificial medium induces a significant loss of egg quality.