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. q

In order to enhance growth, survival and quality during early juvenile stages of marine fish it is important to avoid lipid oxidation problems that are known to cause pathologies and disease. The aim of the present study was to characterise and compare the antioxidant systems in juvenile marine fish of commercial importance in European aquaculture, namely turbot (Scophthalmus maximus), halibut (Hippoglossus hippoglossus) and gilthead sea bream (Sparus aurata). The experiment investigated the interaction of the dietary antioxidant micronutrient, vitamin E, with antioxidant defence systems. Fish were fed diets of identical unsaturation index supplemented with graded amounts of vitamin E. The relationships between dietary and subsequent tissue vitamin E levels were determined as well as the effects of vitamin E supplementation on lipid and fatty acid compositions of both liver and whole fish, on the activities of the liver antioxidant defence enzymes, and on the levels of liver and whole body lipid peroxidation products, malondialdehyde (thiobarbituric acid reactive substances, TBARS) and isoprostanes. Growth and survival was only significantly affected in sea bream where feeding the diet with the lowest vitamin E resulted in decreased survival and growth. A gradation was observed in tissue vitamin E and PUFA/vitamin E levels in response to dietary vitamin E levels in all species. The activities of the main radical scavenging enzymes in the liver, catalase, superoxide dismutase and glutathione peroxidase generally reflected dietary and tissue vitamin E levels being highest in fish fed the lowest level of vitamin E. The indicators of lipid peroxidation gave consistent results in all three species, generally being highest in fish fed the unsupplemented diet and generally lowest in fish fed the diet with highest vitamin E. In this respect, isoprostane levels generally paralleled TBARS levels supporting their value as indicators of oxidative stress in fish. Overall the relationships observed were logical in that decreased dietary vitamin E led to decreased levels of tissue vitamin E, and generally higher activities of the liver antioxidant enzymes and higher levels of lipid peroxides

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Disease problems have emerged as major constraints in aquaculture production. The prophylactic application of antibiotics is expensive and detrimental, i.e. selection of bacteria that are drug-resistant or more virulent and the prevalence of drug residues in reared animals. Probiotics, which compete with bacterial pathogens for nutrients and/or inhibit the growth of pathogens, could be a valid alternative to the prophylactic application of chemicals. A mixture of speci¢c Bacillus strains was designed following a research programme on the ability of numerous Bacillus strains to inhibit a range of pathogenicVibrio strains, to grow under conditions prevailing in shrimp hatcheries and to degrade waste products. These strains were then included in bioassays and challenge tests in order to con¢rm the lack of toxin production and pathogenicity to humans, target organisms and the environment. Here, we report on the performance of a commercially available mixture of Bacillus strains (SANOLIFE s MIC), using data from Asian and Latin-American hatcheries, with Penaeus monodon (Fabricius 1798) and Litopenaeus vannamei (Boone 1931). These results show that probiotics may be a suitable alternative to the prophylactic use of antibiotics. Obviously, minimizing the risk of vibriosis demands a multi-disciplinary approach, including good hygiene and sanitation measures to reduce the input of potential pathogens, as well as a suitable farm management.

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Wild Litopenaeus Õannamei 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 . TL was observed from stage 0 immature to stage 1 early maturing . Later, from stage 1 to stage Ž . 2 mid maturing , a decrease in midgut gland TL was observed. TAG was most responsible for these changes in TL. Lipids were preferentially transferred to the nauplii, which contained relatively high TAG and PC levels. In both midgut gland and ovaries, 16:00, 18:00, 16:1n y 7, Ž . Ž . 18:1n y 9, arachidonic acid ARA; 20:4n y 6 , eicosapentaenoic acid EPA; 20:5n y 3 and Ž . docosahexaenoic acid DHA; 22:6n y 3 were the principal FA. All tissues and nauplii displayed n y 3 ) n y 6 and EPA ) DHA relationships, and contained high proportions of n y 3 highly Ž . unsaturated FA n y 3 HUFA . During sexual maturation, the sum of poly-unsaturated FA Ž . PUFA decreased in the ovaries due to the decrease in n y 6 PUFA such as ARA. The sum of Ž . mono-unsaturated FA MUFA , on the other hand, increased in the ovaries. AA levels were high ) Corresponding author. Laboratory of Aquaculture and Artemia Reference Center, Ghent University, Rozier 44, B-9000 Gent, Belgium. Tel.: q32-9-264-37-54; fax: q32-9-264-41-93.Ž . E-mail address: r.wouters@inve.be R. Wouters . Wouters et al.r Aquaculture 198 2001 307-323 308 in immature, maturing and mature ovaries. They were low in the ovaries of spent females and nauplii. Vitamin E levels were low in immature ovaries, increased substantially during ovarian maturation, and then decreased again upon spawning. High vitamin E levels were retained in the nauplii. The findings of this study, combined with those reported in related studies, suggest the importance of n y 3 HUFA for larval development, of vitamin C for egg development and hatching, and of vitamin E for ovarian maturation and larval development. These nutrients cannot be synthesised de novo by shrimp, and should be included at high levels in the broodstock diet. q