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The inclusion of phosphatidylcholine (PC) in a purified diet is essential for the survival of juvenile lobsters. Attempts to substitute this substance with its alkaline hydrolysis products, fatty acids, an emulsifier or other phospholipids (cephalin, phosphatidylinositol) were not successful. The effectiveness of the PC ingredient in reducing mortality related to a molt death syndrome is dependent upon the source of the compound. Those PC molecules comprised of polyunsaturated fatty acids, were most effective. The lobster's nutritional requirement for PC is probably the result of a low rate of biosynthesis and the physiological role of PC is more probably associated with hemolymph lipoproteins and the transport of lipids, possible cholesterol.

Pigmentation of cultured lobsters is dependent upon the presence of dietary carotenoids. Inclusion of pure or crude carotenoids in a purified diet results in the accumulation of exoskeleton pigments tentatively identified by thin-layer chromatography and spectrophotometric analysis as primarily astaxanthin and β-carotene. Despite the lack of de novo synthesis pure carotenoids such as β-carotene, echinenone, and canthaxanthin are transformed into astaxanthin. The level of pigmentation produced by these biosynthetic precursors is related to the proximity to the astaxanthin end product. A carotenoid extract from crayfish waste dissolved in cod liver oil, and oleoresin paprika were effective in producing pigmentation. Rationale for the choice and use of carotenoid sources for incorporation into artificial feeds to produce natural pigmentation of cultured lobsters is discussed.

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Effective purified and unrefined diets have been developed and evaluated for use in studying the nutrition of lobsters (Homarus sp.). A 4‐month growth experiment showed that the purified diets yielded weight increases nearly 80% of that achieved on a live food diet, with concomitant high survival rates. Lower‐cost unrefined diets supported growth over half of that observed on live food diets. Supplementation of a purified diet with an astaxanthin concentrate derived from crayfish waste enhanced growth significantly, and all the diets tested promoted growth and survival with only 0.2% dietary cholesterol.Growth and survival are the most useful criteria for evaluating crustacean diets, but other factors such as proximate analyses of feeds, physical characteristics such as pellet leaching rates, and measurable physiological effects can provide important supplemental information. Our analysis of some of these factors suggests that pellet integrity and resistance to leaching may not be directly related either to growth, or to levels of binder in the diets.