|Effect of vitamin C incorporation in live food on the larviculture success of aquaculture species|
Merchie, G.; Lavens, P.; Sorgeloos, P. (1993). Effect of vitamin C incorporation in live food on the larviculture success of aquaculture species, in: Seventh forum for applied biotechnology, PAND, Gent 30 September - October 1993, abstracts. pp. 56
In: (1993). Seventh forum for applied biotechnology, PAND, Gent 30 September - October 1993, abstracts. RUG: Gent. 150 pp., more
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VLIZ: Proceedings 
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- Merchie, G.
- Lavens, P., more
- Sorgeloos, P., more
Vitamin C requirements for juvenile and adult aquaculture organisms are relatively well documented, however, for the larval phase only limited information is available with respect to the nutritional effect of ascorbic acid (AA) on growth and physiological condition. Therefore a study was undertaken to upgrade the levels of vit C in the most widely used live food items, being Artemia and Brachionus, through bioencapsulation. Ascorbyl palmitate (AP) was used as the vit C source because of its stable and lipophylic characteristics which allowed its incorporation in booster emulsions. Under standard conditions very high levels of AA could be incorporated into the Artemia nauplii: supplementation of the enrichment emulsion with 20% AP (w/w) increased the AA-content up to 2000 ppm after 24 h enrichment. Also in Brachionus the AA-level changed in function of the concentration of AP applied. 20% AP in the diet enhanced the AA-content in the rotifers 10-fold over 3 days of culture. Elevated levels of a bio-active vit C source can thus be transferred through the live food chain towards the fish or shrimp larvae, in this way providing an important tool to build up stress and disease resistance during larviculture. The effect of these high levels of vit C has been verified for the giant freshwater prawn, Macrobrachium rosenbergii, and two fish species, the African catfish, Clarias gariepinus, and the European seabass, Dicentrarchus labrax, using three different enrichment levels in the live food (0%, 10% and 20%). For M. rosenbergii, no differences on growth nor survival could be observed under standard culture conditions. However, a significantly positive effect on the physiological condition of the postlarvae could be demonstrated when the vit C- boosted live food was administered. It is expected that under suboptimal conditions supplementation of high vit C levels might also enhance production characteristics. For the catfish larvae fed vit C- boosted Artemia, supplemental dietary ascorbate resulted in a significantly positive effect on growth: the 20% AP group weighed 30% more than the control (0% AP) on the final day of the experiment. Evaluation of the physiological condition showed a significantly higher resistance of the larvae according to the dietary vit C level. These differences occurred already on day 2, which might indicate the importance of AA in early development. Seabass larvae were successively fed rotifers (day 4-12) and enriched Artemia nauplii (day 13-46), supplemented with the same three vitamin C enrichment levels. No significant differences in production characteristics nor in stress resistance of the fish larvae could be observed, however, for all salinity stress tests the 20% AP group performed better. Comparing the results for the two aquaculture fish species, with those reported earlier for the larvae of the prawn Macrobrachium, it appears that the requirements for vit C are species specific, and might even differ according to the culture conditions.