Extruded Fish Feed and Its Effect on Fish Production
The production of feeds is an important part for fish farming, because it provides the balanced nutrition that the farmed fishes need. Fish feeds can be various forms, and the granule or pellet fish feed supplies fishes with nutrition in a stable and concentrated mode, which benefits feeding efficiency and fish production. Pellet fish feed has a wide use in fish farms.
Pellet Fish Feed Process
Pellet fish feed can be made by ordinary fish feed pellet mill with no extrusion function or fish feed pellet extruder. The fish pellet feed includes hard pellet feed that is manufactured ordinary fish feed pellet machine and extruded pellet feed produced by fish feed pellet extruder, and the extruded fish feed pellet has an increasingly application to improve fish production.
Extrusion means cooking the mix of fish feed ingredients under high temperature, high moisture and high pressure condition in the extruder. By adjusting parameters of temperature, moisture and pressure, the fish feed producer can make pellets that suit different fish farming methods, such as floating fish feed pellets, sinking fish feed pellets, slow-sinking fish feed pellets, etc.
According to the processing technology, fish pellet feed extrusion is divided into wet-type extrusion and dry-type extrusion. The wet-type extruder is equipped with a conditioner that is working with the steam produced by the boiler, and its final products need to be dried; the dry-type extruder has no conditioner and is operating by friction as the heat producer to produce pellets.
How the Extruded Feed Pellet Affects on Fish Production
Purposes of extrusion processing
1.For cooking to realize starch gelatinization and deactivating anti-nutritional factors
2.For sterilization to eliminate the pathogens in raw materials
3.For expansion to improve the feed quality
4.For texturization to get a porous structure
5.For product shaping to form pellet fish feed easily
Advantages of extruded fish feed pellet for fish production
1.Good palatability helps avoiding feed materials separating to ensure an even nutrients distribution in pellets to guarantee a good fish performance of feed intake.
2.Extruding process requires fine particle size of raw materials, and at the same time, extrusion gelatinizes the starch and denatures the protein, which contributes to high feed conversion and utilization rate.
3.Starch gelatinization and systematism heighten feed caking property so as to improve feed water stability which can reach 12-36hrs. And better water resistance means better nutrients retention and less water pollution.
4.Some fishes need high-fat feed, the fat in extruded fish feed pellet has a high stability and an uniform permeation in pellets, making feed more attractive to increase feed intake of fishes.
5.Through the high-temperature and high-pressure process, many pathogens in materials are removed, so the digestive tract disease is reduced effectively by extruded pellet fish feed.
6.Extruded fish feed can be made in different forms, such as floating feed, sinking feed, and slow-sinking feed, etc. to meet different fish farming methods, reduce feed waste and water pollution.
7.The extruded feed can be sensed as attractant by fishes via varying its shape based on fishes’ preference.
8.The young fishes are free to digest and absorb extruded feed pellets to get an excellent growing.
9.To improve fish feed quality, extrusion process can be used to develop extra feed materials, such as full-fat soybean powder, feather powder, blood powder, etc.
10.It is easy to inspect and control fish feeding condition to keep an optimal fish production.
11.There is low moisture content in extruded fish feed pellet, which facilities long-term storage.
Operation and Support Equipment of Pellet Fish Feed Extruding
Operation of pellet fish feed extruding
1.Raw materials crushing: ingredient particle size is important, and the high-quality fish feed pellet is produced by grinding the ingredients into particles with a size that is not more than 1/3 of the diameter of die hole.
2.Conditioning and water adding:
Steam conditioning is necessary for making floating extruded fish feed as it can improve the internal and external quality of feed, and reduce the wear of feed machine and the waste of power. The finished feed pellet is of superior quality what the conditioning temperature reaches around 90℃.
At the same time, steam conditioning makes an increase in feed expansilbility, which is an ideal factor for the production of high-protein and high-fat fish feed in floating form.
The adjustment of the water adding system in feed inlet and the pressure release system in feed outlet is to control the expansibility and settleability of the final product. And the reduction of feed expansibility and settleability can be realized by decreasing steam addition and supplementing water for conditioning, and reducing pressure release.
Support equipment of extruding fish feed pellet
1.Fish pellet feed conveyor
The freshly extruded fish feed pellet is featured by high temperature, high moisture content, high softness and producing a lot of steam, so the proper conveyor is needed to avoid damaging the pellet. Negative pressure pneumatic conveying and belt conveying are the frequently-used
2.Fish pellet feed drying machine
Product drying is to prevent pellets from mildewing. The drying time, drying rate and drying temperature should be well coordinated and controlled, in addition, a reasonable pellet layer and proper turning over pellets should be kept during drying procedure. Multi-layer mesh belt dryer and high-efficiency fluidized bed dryer are working well for fish pellet feed drying.
3.Pellet fish feed spraying and cooling machine
Post-spraying of fat/oil after drying pellets is aimed at enhancing the water resisting property and palatability of pellet fish feed. But pellet cooling after fat/oil coating is indispensable, so that the packed pellets can have a safe storage with no fat oxidation, surface water condensation and mouldiness.