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Manufactured feeds are an important part of modern commercial aquaculture, providing the balanced nutrition needed by farmed fish. The feeds, in the form of granules or pellets, provide the nutrition in a stable and concentrated form, enabling the fish to feed efficiently and grow to their full potential.
Many of the fish farmed more intensively around the world today are carnivorous, for example Atlantic salmon, trout, sea bass,and turbot. In the development of modern aquaculture, starting in the 1970s, fish meal and fish oil were key components of the feeds for these species. They are combined with other ingredients such as vegetable proteins, cereal grains, vitamins and minerals and formed into feed pellets or flakes. Wheat, for example, is widely used as it helps to bind the ingredients in the pellets.
Other forms of fish feed being used include feeds made entirely with vegetable materials for species such as carp, moist feeds preferred by some species (easier to make but more difficult to store), and trash fish — that is fish caught and fed directly to larger species being raised in aquaculture pens.
Hatchery Feeds Edit
Specialised feeds are produced for fish hatcheries. In species such as salmon and trout, the newly hatched fry first feed from their yolk sacs and then can be fed with starter feeds. Marine species such as sea bass, sea bream, flounders and turbot consume the nutrition in their yolk sacs during the first few days post hatching and then are fed for several weeks on live prey, in the form of rotifers and brine shrimp (Artemia). Special feeds can be used to enrich the nutritional value of the prey. Rotifers are usually bred in the hatchery while brine shrimp are generally collected from the wild, e.g. salt lakes. Manufactured feed alternatives to brine shrimp are becoming available, offering more consistent nutrition and improved sustainability as demand increases with the growth of aquaculture.
Development of Manufactured Feeds Edit
The development of dry pelleted fish feeds to date has two themes. One theme is on improving digestibility and refining the balance of nutrients to match the needs of the different species of fish more precisely at different periods of development. The other theme is to improve the sustainability of the ingredients used. This is being achieved mainly by identifying additional sustainable sources of ingredients, in particular to reduce the need for fishmeal and fish oil. Improving the efficiency of feeding also contributes to sustainability.
Traditionally two of the most important ingredients have been fishmeal and fish oil. These come mainly from the processing of fish from the wild catch, usually pelagic species that are generally not suited to processing for human consumption. Fish sold for human consumption attract a higher price than those used to make fishmeal. The fishmeal fisheries are often referred to as reduction fisheries. The world’s largest reduction fishery is in the Pacific, off the coast of Peru and Chile and is regulated by the governments of those countries. The North Atlantic is another important source of fish for fishmeal and fish oil. Many major suppliers belong to the International Fishmeal and Fish Oil Organisation.
Fishmeal is a brown, flour-like material made by specialist producers that cook, press, dry and grind the fish. The fish oil is effectively a by-product of this process that proves to be a rich source of energy and fatty acids for fish, including the important long-chain omega-3 fatty acids EPA and DHA now linked to the health benefits associated with eating oily fish such as salmon and mackerel. Fish in general also are good sources of many vitamins and minerals and are often recommended as part of a healthy diet by governmental food agencies.
Because the catches of wild fish must be managed at sustainable levels to ensure the stocks continue to be viable, the available supply of fishmeal and fish oil from these resources will not increase.
The global demand for fish from consumers around the world is increasing. Reasons include the growing population, rising average incomes and greater awareness of fish as part of a healthy diet. The yield from the wild catch cannot be increased sustainably, therefore, in the opinion of observers such as the Food and Agriculture Organization (FAO) of the United Nations, aquaculture must fill the gap. Currently the supply of fish from aquaculture approximately matches that from the wild catch, according to FAO figures.
The current drive in research and development is enabling this to happen by supplementing fishmeal and fish oil with vegetable proteins and oils, while ensuring the fish continue to provide the important health benefits for consumers. Other potential raw material resources such as algae are also being explored.
Modern Fish Feed Edit
Modern fish feeds are made by grinding and mixing together ingredients such as fishmeal, vegetable proteins and binding agents such as wheat. Water is added and the resulting paste is extruded through holes in a metal plate. The diameter of the holes sets the diameter of the pellets, which can range from less than a millimetre to over a centimetre. As the feed is extruded it is cut to form pellets of the required length. The pellets are dried and oils are added. Adjusting parameters such as temperature and pressure enables the manufacturers to make pellets that suit different fish farming methods, for example feeds that float or sink slowly and feeds suited to recirculation systems. The dry feed pellets are stable for relatively long periods, for convenient storage and distribution. Feeds are delivered in bulk, in large bags—usually one tonne, or in 25 kilogram bags. Smaller quantities of specialist feeds are supplied for use in fish hatcheries. The three major manufacturers on fish feeds for aquaculture are Biomar, EWOS and Skretting.
Nutrient-balanced fish feed pellets making technology Edit
Equipment needed in fish feed pellets production line Edit
----(to reduce particle size of ingredients to 0.4-0.6 mm) used for processing fish feed raw materials into small pieces
with proper sizes to help further process. And we are the expert in designing and manufacturing several fish feed crushing machine for your choice.
----This fish feed mixing machine is a kind of single-shaft and double-ribbon mixer which is also called ribbon blender. It is widely used to mix powdery feed materials to ensure a high quality of compound feed, and it is a well-working feed mixer for fish and other livestock feed production plants.
fish feed extruder ----(dry type for floating fish feed, wet type for both floating and sinking fish feed ): Extrusionmeans to cook
the mix of ingredients under temperature, moisture and pressure in extruder.
----When the pellets are discharged from the fish feed machine, the pellets temperature can be 90℃ and moisture about 18%. The temperature must be reduced quickly to ambient and moisture to 8%-12% for storage. We can supply two types of feed pellets dryer, one is multilayer mesh belt dryer, the other is gas feed pellet dryer.
----The pellet cooler is widely used to cool finished pellets with high temperature or high humidity. It adopts counter flow cooling theory, and pellets can be cooled completely and evenly through the machine, which is good for the pellet packing and storage. The advantages is energy saving, easy to operate, preferred choice for most users of feed and wood pellets plant.
----The packaging process include filling, wrapping, sealing and other major processes like cleaning, stacking. The packaging process also includes the measurement and conveying packages. Using packaging machine can increase productivity, reduce labor intensity and satisfy the needs of large-scale production and meet hygiene requirements. Our electronic packing machine is suitable for quantitative packaging of granules in food, grain, sugar, animal feeds and so on.
Pelleting process Edit
Grinding: variety of raw ingredients requires size reduction. Particle size is critical to mechanical and
chemical activity. In the crushing process, particle size is determined by a combination of screen size, rotor speed, the size & number of hammer blades, hammer blows, collision with the walls of the grinding
chamber, and the impact among particles. The major factor that affects particle size is screen which
accounts for 70% of what determines the finished particle size, and the rotor speed is also an important
factor. Any material that enters the grinding chamber must be reduced to a size below the diameter of the
screen holes to pass through the screen that covers the mill’s discharge opening. You can control size
reduction through inserting a screen with different sized holes. A main factor in determining finished particle size is the speed of the hammer mill. When the rotor spins, the hammers flail out and impact the material
with great severity causing it to break down. As a result, the higher the rotor speed, the finer end product.
Conversely, if tap the same material with the same hammer at slow rotor speed, it is hard to grind the
material into particles. Therefore controlling the rotor speed can get your ideal particle size.
Mixing: The process is as important as grinding. If you grind ingredients but then you should mix them
homogenously. Powdery feed materials are mixed thoroughly in the mixer to ensure a high-quality of
Things to be noticed during mixing process:
• every formulation has its mixing time. If you get over the mixing time ingredients start to be decomposed
• to put very small amount of ingredients like additives at the middle of filling the mixer.
The production process includes an extrusion process creating pellets with sizes ranging from
less than a millimeter to several centimeters suitable for different sizes and species of fish. This process is
followed by the addition of fatty acids such as fish oil. Pellets are sold bagged or in bulk to fish farmers
around the world.
Characteristics of feeds are produced by extruder: can produce floating, sinking slow sinking feeds
(remember feeding characteristics and habits of fish); because the density can be controlled using different types of screws.
The moist pellets should be dried to a moisture content of 10% or less. Ideally, this should be at low temperature (less than 60 ºC) and with good airflow to dry the pellets as quickly as possible to ensure that heat-sensitive micronutrients such as vitamins are not destroyed.
It is most important when drying pellets to prevent fungal contamination and to avoid an excessive loss of critical nutrients. Fungus can be toxic to fish and to the humans who handle the feed.
When pellets are dry and cool, they should be stored in bags or containers that can be sealed against insects, rats or other pests and to keep out moisture. Avoid using plastic bags because feeds can sweat and this encourages growth of mould.
Produce fish feed that is good for animal health, cost-effective and sustainable:
●Quality nutritional features-denaturing of proteins, gelatinization of starch, reduction of anti-nutriments, flavor enhancement, balanced protein/lipid complexes, increased digestibility,
●attractive texturing and shaping, controlled expansion and density, hygienic salmonella-free pellets
●Ingredient flexibility to process a large range of raw materials (fish flour, vegetable proteins, binders …) continuous processing, fast changeover times
●Full control of process parameters and automation to ensure consistent quality
●Precise shaping and feed dimensions calibrated from 0.5 to 30.0 mm
●Output range, from 25 to over 30,000 kg/h of finished products
●Intensified processing to reduce water and energy consumption
The quality of a feed begins to deteriorate steadily after manufacture. The rate and magnitude of decline can significantly be slowed, through proper feed handling and storage. The following are recommended guidelines for storing dry pelleted fish feed from time of purchase.
1.During transportation and handling, protect the feed from moisture, heat and direct sunlight. Heat and sunlight directly destroy feed nutrients like vitamins.
2.Store the feed in a cool, shaded, dry and well ventilated room. White, wooden buildings with reflective metal roofs are excellent for storing feed. Warm, moist and stagnant air enhances mold growth and attracts insects.
3.Do not stack bags on feed directly against a wall or on a concrete floor. Stack them on top of pallets off the walls of the building to prevent moisture coming in contact with the bags.
4.Protect the feed from rodents, bats, chickens and other animals. The feed can be stored in cages made of coffee wire mesh to keep off such animals.
5.Try to minimize insect contact and infestation.
6.Do not use pesticides or other toxic materials near the feeds.
7.Do not keep feed that has been molded or spoiled. Learn what the normal colour, smell and taste of the feed you use is. If the feed looks gray, blue or green in color; has a sour, musty or mildew odour (smell); or has been wet and has clusters of fused pellets - do not use it.
See also Edit
- Federation of European Aquaculture Producers Aquamedia site