Overview of Expanded Fish Feed Technology
Extruded feed is a type of fluffy and porous feed that has been expanded by feed extrusion machinery.Puffing is a processing technique that reduces pressure on materials after high-temperature and high-pressure treatment, utilizing the instantaneous evaporation of water or the expansion of the material itself to alter certain physical and chemical properties of the material.It is divided into air puffing and extrusion puffing.After feed extrusion, the long-chain structures of organic substances such as starch, protein, and fat are increasingly converted into short-chain structures, and the very soft fibrous structure and cell walls are disrupted.Mustard mold in rapeseed meal, cotton mold in cottonseed meal, and harmful antibacterial growth factors such as antitrypsin in soybean meal are relatively easy to digest.It simultaneously overcomes the disadvantages of poor water quality stability, fast sedimentation rate, and easy loss and waste of feed.The puffing effect is influenced by the ratio of raw materials, starch content, moisture content, and puffing temperature.Combined with puffing characteristics, ensure that the starch raw material in the formula accounts for more than 20%, and use high-temperature resistant additives.
Aquatic feed processed through a feed extruder can float on the water surface for a long time without easily dispersing, facilitating feeding and management, and helping to save labor costs. Extruded feed generally produces less than 1% fines, and high-quality floating fish feed can typically float for about 2 hours. Under normal circumstances, compared to powder or other pellets, it can save nearly 10% of feed, and it is easy to observe and control, reducing water pollution from powdered feed and residual bait.
Technical points:
1. Expand the application scope of feed
In terms of farming methods, floating fish feed can be used for pond farming, paddy field farming, flowing water farming, cage farming, industrial fish farming, and intensive farming, offering wide applicability. In terms of aquaculture species, except for a few benthic fish that are extremely difficult to domesticate and feed on the water surface, many valuable and high-quality species such as perch, snakehead, bowfin, frogs, turtles, and channel catfish can readily consume floating fishery feed. Additionally, conventional farming species such as crabs, grass carp, crucian carp, softshell turtles, common carp, and crayfish also benefit. For species with special physiological functions, such as frogs and perch, using floating feed for breeding is more convenient and advantageous. Farmers with limited breeding experience and extensive management practices are more suited to choose floating fish feed. Some carnivorous fish, such as those that are dark-colored and light-averse, also require domestication or feeding with floating expanded feed at night. For a small number of benthic fish that are extremely difficult to domesticate and feed on the bottom, floating expanded feed should not be used; instead, sinking or slow-sinking expanded feed should be selected.
2. Feeding techniques for extruded feed
(1) Determination of feeding amount
The daily feed intake is about 90% of the fish's satiety level. Based on the feeding behavior of the fish, feeding is generally done 2-4 times a day, with each feeding session controlled within 10 to 30 minutes.
(2) Feeding method
Feeding method for extruded aquaculture feed: Choose a fixed feeding point in a pond or large water area, and feed downwind. Bamboo tubes or PVC pipes can be used to form a square or triangle to contain the floating aquaculture feed. In cage culture and pond fish farming, special measures such as using netting or PVC pipe enclosures are needed to prevent waste of floating feed.
The annual domestic demand for extruded feed produced by feed extrusion machinery is over ten million tons, but the current market only has over one million tons, indicating broad prospects.
