With the development of aquaculture, extruded feed, due to its unique processing technology and significant advantages, is gradually replacing traditional pelleted feed and becoming a new market favorite. Especially in the aquatic feed and pet food sectors, extruded feed is highly favored by farmers due to its high digestibility, long-term water stability, and intuitive feeding monitoring.
I. Processing Technology and Advantages of Extruded Feed
The processing flow of extruded feed covers multiple stages, including raw material receiving, cleaning, crushing, mixing, storage, conveying, conditioning, extrusion, drying, spraying, and cooling. The core function of the extruder is to change the bulk density of the feed, thereby producing buoyant, sinking, or slowly sinking fish feed to meet different aquaculture needs.
II. How Extruders Change the Buoyancy of Fish Feed
Buoyant Feed: In North America, buoyant fish feed is very popular. During its processing, steam and water are injected to ensure the material contains 20% starch, allowing the extruded product to reach a specific temperature and pressure before demolding, forming small air bubbles, thus giving the feed buoyancy. Further drying can enhance the buoyancy effect.
Sinking Feed: Unlike floating feed, sinking feed undergoes less steam injection and increased moisture content during processing. By lowering the temperature, moisture content, and expansion rate of the extruded product, the feed achieves its sinking properties. Suitable for fish species cultured at different water depths.
III. Production Differences Between Floating and Sinking Feeds
Spindle Speed: Floating feed operates at near full speed, while sinking feed operates at a lower speed.
Cooking and Extrusion Degree: Floating feed has a high cooking degree and large expansion degree; sinking feed has a relatively low cooking degree and small expansion degree.
Pressure and Process: Sinking feed production involves an additional pressure relief process, resulting in lower pressure within the barrel.
Preparation Water Addition: Sinking feed requires significantly more water than floating feed.
Template Aperture Ratio: Floating feed has a lower template aperture ratio, while sinking feed has a higher one.
Formulation Differences: Floating feed has a high starch content, which promotes buoyancy; sinking feed has a low starch content, primarily serving a binding function.
IV. Advantages of Extruded Feed
Extruded feed not only improves feed digestibility and utilization and extends water stability time, but also allows for direct observation and control of fish feeding behavior, reducing environmental pollution. The key lies in suitable processes, advanced equipment, highly skilled operators, and high-quality molds, cutters, and other accessories.
