Once techniques for inducing maturation became indentified, diet composition became a critical factor in maintaining broodstock from ouset of maturation to spawning. Nutrition is profoundly important to reproduction of Penaeus, and the success of reproduction is closely related to nutrient ingestion accompanying ovarian development (Bray et al., 1992).

Understanding nutrition-reproduction interactions and determining the nutrient requirements for successful matuaration and spawning are needed to enable year-round large, volume hatchery production of penaeid shrimp for grow-out operations world-wide (Bray et al., 1992).

Diets used for reproduction consist of one or more fresh (or fresh-frozen) marine organism ingredients, with the most common being squid, mussels, clams, shrimp, brine shrimp, and polychaete worms. Additionally, fish, shark, mysids, troca, krill, cockles, crab, and other items have been reported as breeding diets. These ingredients are often chopped into approximately 0.5 to 1.0 cm pieces, rinsed, and fed two to five times daily to breeding populations. Usually only one item is fed per feeding so that a preferred item is not selected. In addition to feeding between one and four fresh feed ingredients, a high quality commercial or prepared diet is often fed, usually around 25% of diet (dry weight basis), and occasionally higher, to around 50%. Even though prepared rations do not serve as a complete substitute for fresh food components at this time, they can provide valuable vitamin/mineral supplements as well as help balance macronutrients. It is noteworthy that the nutritional value of fresh or fresh-frozen animal or plant components can vary in nutritional quality with species, lifestage, season of collection, nutritional condition, freezing method, and storage (Bray et al., 1992).

The need for attention to the lipid portion of the breeders' diets is clear. Because of the rapid rate of ovarian tissue synthesis (ovaries may comprise 10% or more of female weight), accelerated rate of ovarian development with eyestalk ablation, and limited storage function of the digestive gland ("hepatopancreas"), the large amount of lipid in ovary tissue, and limited ability of shrimp to synthesize long carbon chain, polyunsaturated fatty acids predominant in ovaries, inability of shrimp to synthesize sterols, and high phospholipid requirement, the importance of lipid quality is overwhelming. Studies with P. iaponicus, P. monodon, and P. merguiensis have established linoleic, C18:2(n-6), linolenic, 18:3(n-3), eicosapentacnoic, C20:5(n-3), and docosahexaenoic, C22:6(n-3) as essential fatty acids for growth. In other words, dietary sources of these fatty acids are required for growth, as they can either not be synthesized by shrimp or can only be synthesized on a limited basis. In addition to these essential fatty acids, we suggest that arachidonic acid, C20:4n-6, is often deficient in diets for breeding (Bray et al., 1992).

The fatty acid profiles of shrimp ovaries themselves can be used as a clue to appropriate fatty acid constitution of breeders' diets. It is noteworthy that fatty acid profiles of various species are strikingly similar. These data suggest that roughly mimicking these proportions in dietary lipids will aid successful reproduction, and radical departures from these proportions are likely to be detrimental. Two other aspects of lipid metabolism believed to be important to broodstock are the dietary levels of phospholipids and cholesterol. Many of the natural diet components which are at least somewhat successful for reproduction are high in phospholipids, and particularly phosphatidyl choline (Bray et al., 1992).

Shrimp ovaries are typically rich in phospholipids and there are indications that dietary phospholipid quantity and quality may be limiting. A cholesterol (or other sterol) requirement for reproduction has not been determined, but dietary sources of sterols have been shown to be required for growth in crustaceans and are implicated as precursors for synthesis of steroid hormones (Bray et al., 1992).

It is proven that larval quality is dependent on the broodstock diet, because freshly hatched larvae are not feeding, but live on their yolk sac reserves. The quality and quantity of nutrients in egg yolk is dependent on maternal body reserves, capacity for biosynthesis and dietary intake during maturation (Bray et al., 1992).