TYPES OF FEED USED IN AQUACULTURE
Fawole, Femi John
Division of Fish Nutrition, Biochemistry and Physiology
Central Institute of Fisheries Education, (Deemed University), Versova, Mumbai, 400 061, India.
Feed manufacturing can be described as a process concerned with the physical transformation of a written formulation into a compounded “edible” diet for a precise nutritional objective. This association is achieved by mixing components in their solid form (animal meals, oil cakes, cereal products, minerals and vitamins) or liquid form (fish oils, lecithins and certain vitamins and binding agents). Grinding of the largest solid components reduces the heterogeneity of the product and increases digestive utilization to a certain extent. In feed formulation, it is important to first determine the function of a feed, such as supporting maximum growth, feed intake, feed efficiency, or reproductive performance. Once the function or use of the feed has been defined, the type of feed, its formulation, and the appropriate manufacturing technique can be determined. The ultimate goal of diet preparation is to produce a feed that supports maximum production at the lowest possible cost. The choice of manufacturing process to be employed also will depend on the feeding habit of the fish or shrimp to be fed (ie. benthic, pelagic or surface feeder; visual or olfactory feeder; moist or dry diet feeder; rapid or slow feeder) and its physical feed requirements (ie. feed size, bouyancy, texture, palatability, and desired water stability) for all stages of the culture cycle. Both the feed formulation and the feed manufacturing method determine the critical characteristics of feed particles. The feed formulation affects consumption by influencing the colour, taste, and smell of the feed, while manufacturing affects consumption by influencing the feed particle size, shape, texture, density, and buoyancy. A high quality feed is a result of feed formulation and manufacturing methods working in harmony to optimize fish performance. Phase feeding is a term termed used to describe the selection of feed formulation based upon the life stage of an animal. Feed formulations can be categorized by the intended function or phase of production in which the feed will be used. This simplifies communication between feed manufacturers and fish producers. The purpose of phase feeding is to minimize inputs (feed costs) and maximize output (fish performance). Specific feeds can be formulated to increase survival, growth, fish health (non-specific immunostimulation), fish quality, and body composition or to minimize the amount of nutrients in hatchery or farm effluents (pollution reduction). Types of feed
Feeds can be classified based on the stage of the life cycle at which they are targeted. Accordingly, there are starter feeds, fry feeds, fingerling feeds, grow-out feeds, and broodstock feeds. In a practical reality, this doesn’t necessarily imply that for the production of a cultured species all five types of feeds are required or used. 1. Starter Feeds
Starter feeds are given to first-feeding fry or larvae when their endogenous food supply (i.e yolk) is exhausted or about to be exhausted. The transformation from an endogenous to an exogenous food supply is crucial to all aquatic organisms. It is the stage that excessive mortality occurs owing to the inability of larvae to adapt to an exogenous food supply. Starter feeds should be nutritionally complete, easily digestible, and be of the appropriate particle size. It differs in composition and type depending on the nutritional requirement and size of the organism at first feeding; and is generally in the form of fine crumbles or flakes. In many cases, most notably shrimps and some cultured marine finfish; the first feeding is based on live foods rather than on formulated starter diets. 2. Fry Feeds
Fry is the term used for the unmetamorphosed young stage in the life cycle of finfish. It...
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