Fish Nutrition and Feed Technology (2+1)

Unit 12 - Feed additives

12.6.Feed stimulants

Chemo-attractants are synthetic chemicals or natural ingredients containing chemicals, such as free amino acids, betaine etc. Generally, extractive compounds in muscles of molluscs and crustacea are believed to be principal flavour attractants. These attractants are a mix of chemicals comprising nitrogenous compounds including free amino acids, low molecular weight peptides, nucleotides and related compound and organic bases.

The diet presented must have the attractiveness (ie. smell or taste) to elicit an optimal feeding response depending on species in question is a visual feeder or a chemo-sensory feeder. For example, although marine fish held in captivity generally rely on sight to locate their food, they also rely on chemo-receptors located in the mouth or externally on appendages such as lips, barbels and fins. The use of dietary feeding stimulants for these cultivated species is therefore essential to elicit an acceptable and rapid feeding response. In addition, by using feeding stimulants and improving feed palatability, the period of time the feed remains in the water can be reduced, thus minimizing nutrient leaching.

Apart from the above commonly used feed additives, there are other feed additives like amino acids, antibiotics and immonostimulants.

The major synthetic amino acids available for feed supplementation are L-lysine and DL-methionine. These are used as chemattractatnts as well as to supplement deficiencies in a compounded feed. The antibiobtics usage is discouraged as these medicated feed pose health concerns to the consumer due to residual accumulation in flesh of fish and also may pave way for evolution of resistant strains of bacteria to drugs.