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    • Article

      Diet development and evaluation for juvenile abalone, Haliotis asinina Linne: Lipid and essential fatty acid levels 

      MN Bautista-Teruel, SS Koshio & M Ishikawa - Aquaculture, 2011 - Elsevier
      Experiments on diet development and evaluation for juvenile abalone, Haliotis asinina focusing on lipid and essential fatty acid (EFA) levels were conducted. Six isonitrogenous diets were formulated in Experiment 1 (E1) to contain 27% protein with lipid levels at 0, 2, 4, 6, 8, and 10%. Experiment 2 (E2) (EFA levels), used the optimum lipid level (3.59%) in E1 with EFA supplementation of 0.0, 0.2, 0.4, 0.8, and 1.6%. Abalone juveniles [mean initial weight and shell length of 0.60 plus or minus 0.07g and 14.70 plus or minus 0.12mm (E1)], [0.60 plus or minus 0.16g and 15.30 plus or minus 0.73mm (E2)] respectively, were fed these diets at 2-5% body weight in 3 replicates. Feeding trials in 90days/experiment evaluated growth, survival, feed conversion ratio (FCR) and fatty acid composition in abalone tissues. Results showed significantly higher growth rates (ANOVA P<0.05) with abalone fed diets with lipid levels of 2.2%, 3.6%, and 6.1% compared with those containing lipid levels of 7.6% and 9.8%. Abalone fed the lipid-free diet showed significantly the lowest growth rate among treatments. Break point analysis as a function of growth, showed optimum lipid requirement at 3.59%. Survival was high at 95-99% in both experiments. FCR values for D3 and D4 were significantly better compared to D2, D5 and D6 (E1) while no significant differences were found for D2-D6 for E2. Abalone body lipid increased with corresponding increase in dietary lipid. Addition of 18:2n, 18:3n3, and n3 HUFA showed significant improvement in weight gains up to 1.6% supplementation. Fatty acid composition of the lipid samples reflected those of the diets. Total lipid of abalone fed the lipid-free diet showed higher monoenes. Addition of EFA resulted in an increase in both n3 and n6 fatty acids. Lipid incorporation at 3.6% using a 1:1 ratio of CLO and SBO with EFA supplementation (1.6%) is best in juvenile abalone diet formulation.
    • Growth and feed efficiency in mangrove red snapper, (Lutjanus argentimaculatus Forsskal 1775) fed practical diets supplemented with L-ascorbyl-2-monophosphate-Mg 

      MR Catacutan, GE Pagador, E Doyola-Solis, S Teshima & M Ishikawa - The Israeli Journal of Aquaculture-Bamidgeh, 2011 - Society of Israeli Aquaculture and Marine Biotechnology (SIAMB)
      Growth and feed efficiency were determined in red snapper, Lutjanus argentimaculatus (Forsskal 1775), fed diets containing L-ascorbyl-2-monophosphate-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.