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Nutritional value of various dietary lipids to Litopenaeus vannamei juveniles and their essential fatty acid requirements
xiii, 130 leaves : illustrations ; 28 cm.
Shrimp, like all crustaceans, require essential fatty acids (EFA) and phospholipids (PL) for proper metabolism, yet research efforts are needed to gain a better understanding of their metabolism, as well as to establish their dietary requirements throughout the shrimp's life cycle. The present study investigated dietary lipid requirements of juvenile Litopenaeus vannamei. Effects of various oils, alone or in combination with PL, as well as the effect of PL and various dietary lipid levels on quantitative requirements for EFA were evaluated under controlled conditions using semi-purified diets. Dietary PL, provided as soybean lecithin, improved shrimp growth regardless of the kind of dietary oil. However, menhaden fish oil supported the most rapid growth of L. vannamei compared to coconut, linseed, peanut or soybean oil, because it provided more of the EFA, particularly n-3 highly unsaturated fatty acids (HUFA). Neither linoleic (LOA) nor linolenic (LNA) acid, alone (at 0.25, 0.5 or 1.0 % of diet) or in combination (LNA/LOA ratio of 1, 3 or 9), improved weight gain significantly, compared to shrimp fed a basal diet supplemented only with palmitic and stearic acids, suggesting that for this open-thelycum species, requirements for LOA and LNA are negligible. However, significant improvement in the growth response was observed in shrimp fed a diet containing 0.5% of an n-3 HUFA mixture, indicating a higher nutritional value of these fatty acids for L. vannamei. In fact, HUFA like arachidonic, eicosapentaenoic, and docosahexaenoic acids, and the n-3 HUFA mixture, significantly improved shrimp growth when provided at 0.5% of diet, compared to LOA or LNA at 0.5% of diet or the basal diet. Fatty acid analyses of hepatopancreas and muscle generally reflected dietary lipid composition. Quantitative requirements of L. vannamei for EFA did not increase as dietary lipid increased from 3 to 9% of diet. However, elevated dietary lipids did affect total lipid composition of shrimp by increasing lipid deposition in hepatopancreas and muscle tissue. Better understanding of lipid nutrition of juvenile L. vannamei was achieved from the present study. Resulting information can be applied in the formulation of high-quality, inexpensive feeds to use in the aquaculture industry.
"Major Subject: Wildlife and Fisheries Sciences".
Issued also on microfiche from University Microfilm Inc.
Includes bibliographical references (leaves 115-126).