Growth and Feed Efficiency in Mangrove Red Snapper, (Lutjanus argentimaculatus Forsskal 1775) Fed Practical Diets Supplemented with L-ascorbyl-2-monophosphate-Mg

Abstract

Growth and feed efficiency were determined in red snapper, Lutjanus argentimaculatus (Forsskal 1775), fed diets containing L-ascorbyl-2monophosphate-Mg (AMP). Fish (13.39±0.08 g) were fed a practical diet without vitamin C supplement for four weeks then stocked in twelve 650-l tanks at 30 fish/tank and fed one of four practical diets containing AMP at 0, 60, 180, or 540 mg/kg dry diet for 17 weeks. Survival rates in all treatments were similar (88.9-98.9%). Fish fed the 0 or 540 ppm diets had inferior final average weights, protein efficiency ratios, and feed conversion ratios than fish fed the 60 or 80 ppm diets (p<0.05). Growth of fish fed the 0 or 540 ppm diets slowed down on day 60 and fish fed the AMP-free diet exhibited clinical signs of vitamin C deficiency with a soft body and a significantly high (p<0.05) hepatosomatic index. Ascorbic acid in brain and liver tissues rose with the level of dietary AMP. Fish fed the 540 ppm diet had significantly lower hematocrit (p<0.05) than fish fed the 60 or 180 ppm diets. Histological analysis of the liver and kidney of fish fed the 180 and 540 ppm diets showed changes indicative of possible toxic effects. Based on growth, feed efficiency, tissue histology, and hematocrit level, AMP at 540 ppm is toxic to snapper. Thus, supplementation of 60 ppm AMP or its equivalent 26 ppm ascorbic acid in practical diets for red snapper promotes optimum growth and feed efficiency and prevents vitamin C deficiency symptoms. The IJA appears exclusively as a peer-reviewed on-line open access journal at http://www.siamb.org.il Sale of IJA papers is strictly forbidden.

Juvenile mangrove red snapper (Lutjanus argentimaculatus) is euryhaline but utilizes feed better in seawater than in brackish water

“…The growth performance of juvenile fish in the present study, in terms of SGR, was within the range observed in other euryhaline carnivorous fish [14, 28,29]. Corroborating with our results, SGR values ranging from 1.45-1.60% BW/day were reported in mangrove red snapper with an initial weight of 13.4 g after receiving a practical diet with 45.4% crude protein for 17 weeks [30]. However, the SGR of fish in this study (1.78 to 2.08%/day) was inferior to the value reported by Chi and True [9] of ∼4.33%/day.…”