Recent Nutrition Research in Tilapia,Oreochromis niloticus × O.aureus and Grass Shrimp,Penaeus monodon

摘要

Several studies have reported on lipid requirements of various tilapia,however,the results of these studies gave contradictory results as to the requirement of tilapia for dietary n-3 and n-6 polyunsaturated fatty acids.We have demonstrated that n-3 highly polyunsaturated fatty acid as well as n-6 fatty acid are essential for maximum growth of juvenile hybrid tilapia.Vitamin E is a major membrane-bound antioxidant present in the lipid of cell membranes and lipoproteins,where it protects polyunsaturated fatty acids against free radical-mediated peroxidation.The vitamin E requirements of tilapia has thus been re-evaluated based on the recent lipid nutrition information and the results indicated that the optimum dietary vitamin E requirements in juvenile tilapia are 42-44 mg vitamin E/kg and 60-66 mg vitamin E/kg in 5% and 12% lipid diets,respectively.High supplementation level(3X adequate) of vitamin.C could spare vitamin E in diets for tilapia.In minerals,ferric citrate has been demonstrated is half as effective as ferrous sulfate in meeting the iron requirement of juvenile tilapia.Dietary sodium(Na) requirement for juvenile hybrid tilapia reared in fresh water is 1.5 g/kg diet,whereas no dietary Na is required for tilapia reared in seawater. Vitamin C is an essential nutrient for crustaceans.Traditionally L-ascorbic acid(AA) was the source of vitamin C used in shrimp feed.However,AA is unstable.Several stable forms of vitamin C derivatives,namely L-ascorbyl-2-sulfate(C2S),L-ascorbyl-2-monophosphate-Mg(C2MP-Mg),L-ascorbyl-2-monophosphate-Na(C2MP-Na) and L-ascorbyl-2-polyphosphate(C2PP) have been compared their biopotency in meeting the vitamin C requirement of Penaeus monodon.Results indicated that the biopotencies of these compounds are C2MP-Mg(1) >C2Mp-Na(84%)>C2PP(64%)>C2S(25%).Dietary ascorbate enhances immune responses in P.monodon and different ascorbate sources may affect the immune responses differently.Our study also suggests that increase of dietary vitamin C improves haemocyte respiratory burst response and growth and prevents tissue copper(Cu) accumulation in P.monodon fed with high dietary Cu.