Patrick Lavens

Penaeid shrimp broodstock nutrition: an updated review on research and development

This paper reviews the current knowledge on shrimp broodstock nutrition with special reference to developments during the last decade. Biochemical studies and diet studies are discussed with the aim of identifying the nutrients that are important to sustain optimal shrimp maturation, reproduction and offspring quality. Additionally, an overview is given of the efforts to reveal the nature of maturation-stimulating factors in fresh food, and of the use and performance of commercial and experimental artificial diets.

Lipid composition and vitamin content of wild female Litopenaeus vannamei in different stages of sexual maturation

Wild Litopenaeus Oannamei females in different stages of sexual maturation were sampled, Ž. including spent females and their nauplii, for determination of the lipid content, lipid class LC Ž. composition, fatty acid FA composition, vitamin C content and vitamin E content. Free FA Ž. Ž . Ž . Ž . FFA , triacylglycerol TAG , phosphatidylcholine PC and sterol esters SE were the dominant Ž. LC in the midgut gland. TAG and phospholipids PL , mainly PC and phosphatidylethanolamine Ž. Ž . Ž . PE , were the dominant ovarian LC. Neutral lipids NL prevailed over polar lipids POL in midgut gland lipids, while ovarian lipids displayed an inverse relationship. An increase in ovarian Ž. Ž

Variations in lipid classes and fatty acid content in tissues of wild Macrobrachium rosenbergii (de Man) females during maturation

Abstract This study describes the variations in total lipid, lipid classes and fatty acids in the midgut gland (MG), ovary, and muscle tissue of wild-caught Macrobrachium rosenbergii to elucidate the importance of these components during sexual maturation. Mature females were captured in the Mae Klong River, Thailand, from July to September 1998, and divided into five groups according to their ovarian development. Total lipid levels in the ovary increased with maturation, but no concomitant decrease in MG lipids was observed. Thus, the lipid requirements of the developing ovary are thought to be more dependent on the immediate ingestion of dietary lipid than on MG reserves. Higher proportions of neutral lipids (NL), mainly triacylglycerols (TG), were observed in both MG and ovary, whereas polar lipids (PL) predominated in muscle. In the ovary, total NL increased significantly along with maturation mainly due to an increase of TG and sterols. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) formed the bulk of ovarian PL and also increased significantly as maturation progressed. Major fatty acids in both MG and ovary were 14:0, 16:0, 18:0, 18:1 n −9, 18:2 n −6, 18:3 n −3, 20:4 n −6, 20:5 n −3 and 22:6 n −3. Significant increases in the levels of saturated and mono-unsaturated fatty acids were observed in both MG and ovary. The levels of n −3 highly unsaturated fatty acids (HUFA), particularly 20:5 n −3, decreased in the MG as ovarian development proceeded. In contrast, an increase in the ovarian contents of n −3 HUFA was detected.

Ammonia toxicity as a criterion for the evaluation of larval quality in the prawn Macrobrachium rosenbergii

The feasibility of a short-term ammonia toxicity test as an evaluation criterion for larval quality was assessed in three trials. In each one, Macrobrachium rosenbergii larvae originating from the same spawn were nutritionally differentiated in two groups by feeding them either a nutrient-rich (Artemia nauplii enriched for 24 h with n-3 highly unsaturated fatty acids (HUFA) and ascorbic acid (AA)) or a nutrient-poor diet (Artemia nauplii starved for 24 h). Throughout their development, larvae from both treatments were exposed during 24 h to six concentrations of total ammonia (NH(4)(+)+NH(3)) and a control (no ammonia added). Based on mortality rates, the median lethal concentration for 50% of the population (LC(50)) was estimated. As expected from earlier work, larvae fed the optimal diet presented higher n-3 HUFA and AA contents as well as higher growth and metamorphosis rates. From the moment the effect of diet quality was analytically detectable in the tissues of the larvae, the ammonia test was able to distinguish both groups of larvae. Differences in ammonia tolerance were observed as early as larval stage 4 and remained evident throughout larval development. The short-term ammonia toxicity test proved to be a valuable, sensitive and reproducible criterion for the establishment of larval quality.

Antioxidant effect of dietary tocopherol and ascorbic acid on growth and survival of Litopenaeus vannamei postlarvae

The nutritional effect of vitamin E in dietsfor Litopenaeus vannamei postlarve (PL19)was investigated. Four formulated diets withdifferent combinations of α-tocopherylacetate (α-TA), ascorbic acid (AA) andhighly unsaturated fatty acids (HUFA) weretested, using four replicates.No significant differences in survival wereobserved among treatments after 34 days offeeding. However, shrimp fed with a dietcontaining 2% fish oil (low n-3 HUFA content),200 mg.kg−1 α-TA and100 mg.kg−1 AA (diet H/E/C) showedsignificantly better growth than those fed adiet supplemented with 5% fish oil (high n-3HUFA content), 200 mg.kg−1 α-TA and100 mg.kg−1 AA (diet H+/E/C). Shrimp fedwith a diet containing 5% fish oil,900 mg.kg−1 α-TA and100 mg.kg−1 AA (diet H+/E+/C) showed a significantly higher tissue level of n-6 PUFAthan postlarvae fed diet H+/E/C. No definiteconclusion could be drawn about a possibleinteraction between α-TA and AA, since acomparison of the diet containing 5% fish oil,200 mg.kg−1 α-TA and700 mg.kg−1 AA (H+/E+/C+) and the dietH+/E/C did not show any significant differencesin any of the measured parameters. Theantioxidative status of the shrimp tissue(measured by means of the thiobarbituric acid(TBA) assay and expressed as nM malonaldehyde(MA) per gramme dry weight) was equal for alltreatments. Nevertheless, there was a slightlylower MA value with the diet H+/E/C+,indicating that AA may be an effectiveantioxidant in the aqueous phase and at thewater/lipid interface of the tissue. The tissuelevels of α-T and AA were highlydependent on the amounts in diets and nocorrelation between α-T and AAincorporation could be observed.