Fish and shrimp feed

Some introduction and problem solving of ring die pellet machine

With the development of aquaculture, the demand for fish feed has increased dramatically. The quality of fish feed directly determines the efficiency of aquaculture and the health of fish.

The unique transformation of fish feed from loose raw materials to pellets is inseparable from the production of a ring die pellet machine.

Through its extrusion molding principle, it transforms raw materials such as fish meal and soybean meal into the fish feed we are familiar with. Today, we will explain how fish feed is transformed from raw materials to this form in the “hands” of a ring die pellet machine.

A Brief History of Fish Feed

Fish feed is a specially formulated feed for farmed fish. It provides the energy and nutrients necessary for growth, development, and reproduction, while also ensuring palatability, digestibility, and environmental friendliness.
In the past, fish relied on natural resources. While this period’s feeding methods were simple and crude, they laid the foundation for the subsequent development of systematic fish feed.

Early fish farming practices, as documented in various sources, primarily relied on natural bait found in the water, supplemented with agricultural byproducts such as rice bran and wheat bran.
Although rice-fish farming systems were later widely adopted in Asia.

European monasteries developed unique fish farming systems, and the Inca civilization in South America pioneered terraced fish farming, these systems all presented numerous challenges, such as nutritional imbalances, high levels of impurities, and unstable supply. Ring die pellet mills can now address these challenges.

What is a Ring Die Pellet Mill?

A ring die pellet mill is a mechanical device used to compress powdered raw materials into high-density pellets. Its core component is a pelletizing chamber with a ring die and several rollers. It is widely used in feed processing, biomass energy, and organic fertilizer production.

This equipment offers high output efficiency and is suitable for large-scale continuous production, especially for large fish feed manufacturers.

How does a ring die pellet machine produce fish feed?

1. Pre-compression: The mixed raw materials are fed into the pelletizing chamber. The rotating rollers pull them into the wedge-shaped space between the ring die and the press rollers. As the gap gradually narrows, the raw material density increases.

2. Extrusion: Under the continuous thrust of the press rollers, the raw materials pass through the circular holes of the ring die. Pressure and friction create a specific structure and are extruded.

3. Cutting and shaping: The extruded fish feed is cut by a high-speed rotating cutter, forming pellets of uniform length.

What are the advantages of a ring die pellet machine? Why has it become a must-have?

The following four reasons explain its popularity:

1. Uniform pellet density, reducing aquaculture waste:

Fish feed by sensing, catching, and swallowing. If the pellet density is incorrect, much feed will remain uneaten, leading to water pollution. A ring die pellet machine can precisely control the pellet settling rate by adjusting the die aperture and compression ratio, thereby reducing costs.

2. Nutrient retention:

Although the ring die pellet machine generates high temperatures during the extrusion process, the raw materials remain in the pelletizing chamber for less than 20 seconds, a “high-temperature, short-time” process.

Nutrients such as vitamins and amino acids are largely preserved, resulting in a high retention rate, making it ideal for juvenile fish feeds, which require high levels of nutrients.

3. High pellet forming rate:

The ring die pellet machine can produce a variety of fish feed types with a high pellet forming rate. It can produce feed tailored to the different growth stages and physiological needs of fish, adapting to a variety of raw material combinations.

4. High production efficiency:

Due to the large-scale development of aquaculture, there is a huge demand for fish feed products, but the output of many production equipment is not high. However, the ring die pellet machine can produce several tons of output per hour. It is very suitable for medium-sized and larger farms and feed factories.

What are the common raw materials used in fish feed?

Five common raw materials are used in fish feed:

1. Protein:

Protein is an important nutrient for fish growth and development. This type of raw material primarily provides a source of protein for fish. Common protein raw materials include plant proteins, such as soybean meal and rapeseed meal; animal and insect proteins, such as fish meal, meat and bone meal, and insect meal, are also available.

2. Energy Raw Materials:

Provides energy for fish to maintain vital activities and growth. Common raw materials include corn, wheat, bran, and rice bran. These raw materials are high in energy and relatively inexpensive, making them excellent choices as energy raw materials.

3. Minerals:

These are essential substances for normal fish metabolism and growth. Among them are calcium hydrogen phosphate and dicalcium hydrogen phosphate, which are essential for fish bone growth; stone powder, which contains calcium carbonate, is used to supplement calcium; and salt regulates the osmotic pressure in fish.

4. Vitamins:

These include vitamin A, vitamin D, vitamin E, vitamin K, and B vitamins, which are crucial for the normal functioning of various systems in fish. 5. Additives:
Attractants, binders, and mildew inhibitors are added to the raw materials to prevent mold and to ensure that fish can eat the food.

Types of Fish Feed

Fish feed can be categorized into the following types based on the fish species, their living environment, and their feeding habits.

1. Pellets:

The most common feed types can be divided into three main categories: The first is buoyant, with a density lower than water. When added to the water, it floats on the surface or upper layers of the water. This is suitable for surface fish such as silver carp, bighead carp, and grass carp.

The pellets float for a long time, making them easier for top-dwelling fish to consume and reducing residual water pollution.

The second is submersible, with a higher density. It sinks quickly to the bottom upon entry. This is suitable for fish such as black carp, catfish, and carp. Some feeds are also protein-rich, catering to both carnivorous and omnivorous fish.

The last is slow-sinking, which sinks slowly upon entry. This is suitable for mid-dwelling fish such as sea bass and tilapia. Starch gelatinization and the addition of oils slow down the sinking rate.

2. Powdered feed:

Primarily used for juvenile fish, the particles are typically less than 0.5mm in diameter. This feed is made by ultrafinely grinding the raw materials (using an ultrafine grinder) and then mixing them. Besides juvenile fish, filter-feeding fish such as silver carp can also be used.

These fish either have small mouthparts or use their gill rakers to filter powder from the water for nutrition.

3. Extruded feed:

This feed is relatively expensive but suitable for high-end aquaculture. Processed using a high-temperature, high-pressure extruder, the pellets have a porous structure and adjustable density.

The starch has a high gelatinization degree, making it easily digestible. The high fat content makes it suitable for fish with high energy needs and offers a long shelf life, making it suitable for industrial aquaculture.

4. Paste feed:

This feed is made by boiling and blending the raw materials into a paste. A binder is added to maintain its shape. It is suitable for pre-spawning and juvenile transition periods.

Fish Feed Storage

The main ingredients in fish feed are sensitive to environmental changes. Temperature and humidity can cause the feed to deteriorate, so careful care is required.

1. Environmental Considerations:

The temperature should not exceed 25°C. Otherwise, the fat in the feed will oxidize and become rancid more quickly, producing an unpleasant odor and destroying fat-soluble vitamins. The humidity should not exceed 60%.

Otherwise, the feed will absorb moisture, causing a high moisture content, mold growth, and caking.

2. Selecting Appropriate Containers:

When unopened, carefully inspect the original packaging for damage. Cover the outer layer with plastic film to enhance moisture resistance. After opening, if the fish feed is for home ornamental fish or small-scale aquaculture, food-grade storage barrels can be used. For small and medium-sized fish ponds, galvanized iron drums can be used. Large-scale farms require stainless steel silos.

3. Appropriate Stacking:

When stacking, pay attention to spacing between the feed. Maintain a certain distance to facilitate air circulation, inspection, and handling. Also, be careful not to stack too high, as this will cause the feed to clump. Ensure that different types of fish feed are stored separately, away from pesticides, fertilizers, and other chemicals to prevent contamination. Keep the feed away from heat sources.

4. Regular Inspection:

Observe the fish feed for color issues, lumps, feel, and pellet hardness. Samples should be taken for testing and any spoiled feed should be disposed of.

FAQs

1. What is the output capacity of your machine?

A: Our ring die pellet mill currently has a standard capacity of 1 to 10 tons per hour. We can customize it for higher requirements.

2. What material is your machine made of? What is the diameter of the ring die?

A: Based on common models on the market, our equipment typically uses alloy steel for better wear resistance. Furthermore, the diameter of the ring die is customized based on your desired product.

3. What raw materials are suitable for processing with your equipment?

A: Our equipment can process feed, biomass, and other pellet materials.

4. Do you provide after-sales service?

A: We offer a one-year warranty, parts replacement, installation and commissioning, and training services.