Glossary of Hatchery terms

Glossary of Hatchery Feed Terms - E - F

October 9, 2019


Extruder, Extrusion Cooker  —  A continuous cooker employing a screw, that applies pressure, high temperature and mechanical sheer to produce feeds. The process gelatinizes the starchy components, denatures proteins, stretches or restructures tactile components and causes exothermic expansion of the extrudate. When the feed leaves the die, it expands and the pellet that is formed will float.


Fatty acid  —  Organic acid composed of carbon, hydrogen and oxygen that combines with glycerol to form fats.

Fatty acid, essential- (FAE) — Fatty acid, which cannot be synthesized by an organism and must be supplied in the diet to avoid a dietary  deficiency.

Fatty acid, highly unsaturated - (HUFA) —  Fatty acid containing three or more double bonds between the carbon molecules.

Fatty acid, polyunsaturated - (PUFA) — Fatty acid containing two or more double bonds between the carbon molecules.

Feed coefficient — Feed consumption per unit weight increase.

Feed conversion (FC) — In aquaculture, a term usually used in relation to defining the performance of fish diets. It is used to express, in kilos, the dry weight of a specific feed required to produce one kilogram of fish flesh, e.g. FC = 2.8.

Feed conversion (efficiency), absolute — In semi-intensive aquaculture: an index obtained by dividing the dry weight of feed distributed by the extra growth believed to have been obtained
Feed conversion (efficiency), relative — In semi-intensive aquaculture: an index obtained by dividing the dry weight of feed distributed by total fish production, including that obtained from  available natural food.

Feed conversion efficiency (FCE) — Live weight gain over a defined period expressed as a percentage of food intake during that same period; it is equal to: (W/F) x 100, where W is the live weight gain and F the weight of the dry food fed over the period.

Feed conversion efficiency, specific - (FCEs) —  Measurement of fish growth. Is equal (in percent) to G/R x 100, where R is the food ration in percent weight of body weight per day and G is the specific growth rate.

Feed conversion ratio (FCR) — Ratio between the dry weight of feed fed and the weight of yield gain. Measure of the efficiency of conversion of feed to fish (e.g. FCR = 2.8 means that 2.8 kg of feed is needed to produce one kilogram of fish live weight). 

Feed efficiency ratio (FER) — The inverse of the feed conversion ratio; the live weight gain per unit dry weight of feed; for example 0.35:1 if a gain of 0.35 kg live weight is produced by one kilogram of dry feed.
Feed formulation — Feed formulation is a calculation to decide how much of each raw ingredient to use to prepare a feed. The general objective of feed formulation is to mix ingredients of differing nutritional quality so as to obtain a balanced diet whose biologically available nutrient profile approximates to the dietary needs of the animal in question. Many manufacturers use the "least cost" method, where the ingredients of a feed may change regularly according to the availability and price of different feedstuffs, but the final formulation of the feed (in terms of percentage and overall quality of protein, fats, etc.) will remain constant.

Feed rate — Quantity of feed given to animals on a daily basis, expressed as percent body weight per day or number of organisms consumed per hour.

Feed utilization — The weight increase per unit of utilized feed.

Feed, closed-formula — A diet for which the  formula is known only to the manufacturer.

Feed, complete — A nutritionally adequate feed to be fed as the sole ration and capable of maintaining life and/or promoting.

Feed, compound — A feed composed of several ingredients of vegetable or animal origin in their natural state, fresh or preserved, or products derived from the industrial processing thereof, or organic or inorganic substances, whether or not containing additives, for oral feeding in the form of a complete feed.

Feed, expanded — Type of hard, relatively low-density pelleted feed with a slow sinking rate. Can be used to produce high-oil diets.

Feed, floating — Prepared feed pellets produced by the extrusion process under conditions that  result in a density that will allow them to float at the water surface for extended periods.

Feed, microbound — feeds that are held together with binders from within the mix of ingredients. These can be either crumbles or on-size feeds.

 Feed, microencapsulated — A microdiet consisting of ingredients that are encapsulated by a shell, or membrane.

Feed, moist — Feed which contains from 18 to 45 percent water.

Feeding value — A term referring to the nutritive value of different feeds, i.e. expressing the amount of nutrients furnished by each feed and the degree of their digestibility.

Fertilization  —  The addition of nutrients (fertilizers) for the purpose of artificial enrichment in order to stimulate primary production as the base of the food chain.

Fingerling —  Related to any fish from advanced fry to the age of one year from date of hatching regardless of size, usually applied to trout of about 10-70 g in weight, or 8-15 cm fork length. The term is, however, not rigidly defined.
First feeding — Term given to describe the period of transition between sac fry and fry, when the fish begin to look for food after having exhausted most of their yolk sac. 

Flake — A feed ingredient rolled or cut into flat pieces with prior steam conditioning.

Floc — A coagulated mass of particles.

Food, live — Common, non-specific term used to describe the living microscopic organisms (e.g. rotifers, artemia) used to feed the larvae of certain finfish and shellfish before  being weaned on artificial diets.

Fry — A term used to describe a fish at the post-larval stage. All stages from hatchling to fingerling stage can potentially be covered by "fry".

Fry, advanced — Any young fish from the start of exogenous feeding (after the yolk is absorbed). For salmon and migratory trout, see Parr.

Fry, swim-up — Term usually used in relation to salmonid culture referring to fish fry, which have just absorbed almost all of their yolk,  becoming buoyant and ready to consume food. Swimbladder inflation occurs at this point.