Feed palatability and the alternative protein sources in shrimp feed

Feed palatability in carnivorous aquaculture species, shrimps in particular, has been crucially related to the presence of compounds acting as attractants that are commonly associated with the prey components under wild conditions. Thus a nutritionally adequate and organoleptically-pleasing diet is essential to achieve satisfactory intake and growth in shrimps. Historically, fishmeal has been an essential dietary component of intensive shrimp cultures because of its nutrient composition and compounds of high attractability. However, in recent years the fishmeal supplies have been dwindling due to over hunting, a diminishing natural fish-stock, elevating prices and market volatility. This has led to search for cheaper sources of suitable protein as fishmeal substitutes. To improve the palatability of diets, various substances have been investigated for their effectiveness in aqua-feed including natural feed ingredients and synthetic flavor substances. For crustacean, attractants characteristically are of low molecular weight, water and ethanol soluble, and amphoteric or basic compounds that are released from potential prey items. Compounds such as free amino acids, especially taurine, hydroxyproline, glycine, arginine, glutamic acid and alanine have been identified to stimulate feeding in shrimps. The same has been identified with organic acids, nucleotides and nucleosides, betaine, and some small peptides. Palatability also has been associated with animal’s past experience with the feed. Understanding the factors that regulate feed palatability is therefore primary for successful shrimp culture