1. Reasonably design of Fish Feed Formula
Before designing fish feed pellets formulation, we should make certain the species and growth stage of fish to determine the content of nutrients including protein, energy and so on. The fish feed pellets formulation
should not only meet the fish’s demand for protein, but also have a reasonable proportion of energy to protein, because too high or two low proportion of energy to protein will be bad for the growth of fish. In addition to nutrition, satiety of fish should be also taken into consideration when formulating fish feed pellets. At different growth stage, the fish’s demand for nutrients is different, for example, the protein content of feed pellets for carp fry should be 43%-41%, fingerlings 37%-42%, and adult fish 28%-32%.
2. Choose Suitable Raw Materials
Choosing raw materials for feed pellets shoud be based on three principles: quality and cheap, stable source and convenient transportation. When conditions allow, the more the kinds of materials are, the better the feed pellets will be.In this way, the essential amino-acid in the feed can achieve a balance and satisfy the fish’s demand for amino-acid to the greatest extent. On the other hand, the moldy and spoiled mateirals can easily cause fish disease, so they mustn’t be used for feed. Materials like cottonseed cake and
rape seed cake should also be limited to 10% in feed because they contain anti-nutritional factors such as gossypol and glucose thioglycoside which will affect the fish growth if used in large amount. Many farmers like to use cheap greaves and meat cake to make fish feed pellets, but this kind of materials usually mixed with a lot of animal fur and feather which will impact the grinding and pelletizing process and cause digesting problem of fish. Last but not least, the moisture content of mateirals should be about 12%-13% after drying. Too high moisture content will reduce the nutritive value of feed pellets, cause mould and reduce the storage time.
3. Control Fish Feed Pellets Processing Technic
The process of making your own fish feed pellets generally includes grinding,mixing,pelletizing, sometimes conditioning.
Grinding can increase the contact area between feed and animal digestive enzyme, improve the digestive absorption of substance, nitrogen and energy and reduce the feed coefficient. Generally, the materials for fish feed pellets should all pass through the 40 mesh sieve and not more than 20% left on the 60 mesh sieve. For making carp feed pellets, the optimal grinding fineness is 1.7mm.
Mixing is an important part to ensure compound fish feed pellets quality. Uneven mixing will lead to uneven distribution of variety nutrients in the fish feed pellets and then affected greatly the fish growth, even cause death of fish in severe cases. Here we can adopt fish feed mixer to get the best mixing result.
Conditioning is a process where the hot steam is injected into the conditioner of fish feed extruder and then feedstuff is subject to mixing and heating under hot steam before being forced through a die mould. In this way, materials have fully gelatinization of starch by a combination of hot steam and mechanical shear/mixing.
Catfish Feed Production Formulation & Process