Improvement of Quality of Red Sea Bream Eggs by Feeding Broodstock on a Diet Containing Cuttlefish Meal or on Raw Krill Shortly before Spawning

Abstract

Red sea bream broodstock were fed on various diets of different nutritional quality for either 26 days or shortly before spawning to clarify the effect of the duration of the period over which diets are fed on spawning and egg quality.
The percentage of buoyant eggs in the control group receiving the white fish meal diet was 42.7%, slightly lower than that hitherto obtained by the diet. Addition of 200mg of DL-α-toco-pheryl acetate to the diet elevated the value to 77.9%. The value was also effectively improved by replacement of cuttlefish liver oil with krill oil extracts. Substitution of cuttlefish liver oil by corn oil resulted in deterioration of egg quality. In the eggs produced by the broodstock fed on a diet containing cuttlefish meal as a protein source, percentage of buoyant eggs was as high as 98.4%. Feeding broodstock with frozen raw krill after the fish had previously been fed on a diet fortified with vitamin E for 26 days also resulted in elevation of the percentage of buoyant eggs. A similar improvement was also observed in a group given a diet containing corn oil, the original value was 30.6% it was elevated to 91.7% by feeding frozen raw krill shortly before spawning.
Consequently, total quantity of fish seed produced by each experimental group calculated from the number of buoyant eggs, hatchability and abnormality in both eggs and hatched larvae was highest in the cuttlefish meal group, followed by the frozen raw krill groups. Thus in fishes like red sea bream which can accept diet actively even during spawning, the quality of diets given to broodstock even shortly before spawning becomes very important for their reproduction.