Rational design of feed formula

Before designing the formula, the species and growth stages of the fish must be clarified in order to determine the level of nutrients such as protein and energy in the feed. It is necessary to meet the protein needs of fish growth, but also to make the ratio of energy and protein moderate. Too high or too low energy protein ratio is not conducive to fish growth. When designing the formula, the relationship between feed nutrition level and bulk density should also be considered, so as to ensure that fish can take in sufficient nutrition and make them feel full. Fish mainly use protein as an energy source, and the utilization rate of fat and sugar is low, so the demand for protein is higher than that of livestock and poultry. Different stages of fish growth have different requirements for various nutrients. For example, the protein content in feed for juvenile carp is 41% to 43%, that of fingerlings is 37% to 42%, and that of adult fish is 28% to 32%.self-mixing-method-of-fish-feed

Selection of feed ingredients

The selection of raw materials should be based on the principle of high quality and low price, stable supply and convenient transportation. When conditions permit, the more types of raw materials, the better, so that the essential amino acids in the feed can be balanced as much as possible, and the needs of fish for various essential amino acids can be satisfied to the greatest extent. Moldy and deteriorating raw materials must not be used. Moldy and deteriorating raw materials contain a large number of germs and toxins. For example, moldy corn contains highly toxic aflatoxin. These feeds can easily cause fish diseases after feeding. Although raw materials such as cottonseed meal and rapeseed meal are cheap and have high protein content, they contain anti-nutritional factors such as gossypol and glucosinolate respectively, excessive use will affect the growth of fish, so the amount should be limited , generally no more than 10%. Many farmers like to use cheap oil residue and meat cakes, but such raw materials are mixed with a lot of animal fur, which affects the smooth progress of the crushing and granulation process, and fish are not easy to digest after eating. The fat contained in the oil residue and meat patties is saturated fat, and the utilization rate of saturated fat by fish is low. Excessive intake of rancid fat will also cause fish to suffer from fatty liver and other diseases, so the amount of such raw materials should be Control it below 5%. In addition, when selecting raw materials, attention should also be paid to the moisture content of the raw materials. Excessive moisture will reduce the nutritional value of the feed, and may also lead to mildew of the feed and shorten the storage time of the feed.

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Process control

The technological process of producing self-prepared feed in rural areas generally includes crushing, mixing, and conditioning before pelleting where conditions permit.

Crushing can increase the contact area between feed and animal digestive enzymes, improve the digestion and absorption of nitrogen and energy, and reduce the feed coefficient. It is not good if the crushed particle is too coarse or too fine. Generally, the raw materials of fish compound feed should be crushed until all of them pass through a 40-mesh sieve, and the 60-mesh sieve should not exceed 20%.

Mixing is the main link to ensure the quality of compound feed and improve the effect of feed. Breeding practice shows that if the components in the compound feed are mixed unevenly, the growth of fish will be significantly affected, and in severe cases, it will even lead to death. This is because uneven mixing makes the distribution of various nutrients in the same batch of feed uneven, and the effect of the formula cannot be achieved. Some additives, such as heavy metals, will cause fish poisoning and death if the local concentration is too high.

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Rational use of additives

When producing self-prepared feed, vitamin and mineral premixes produced by specialized manufacturers can be selected, and added reasonably according to the species and growth stages of farmed fish. The production of self-prepared feeds can also prepare a small amount of special feeds according to their own needs. For example, according to the incidence of fish in their own ponds, symptomatic drugs can be added to the feed to make baits for easy use. When using pharmaceutical additives, you must abide by the relevant laws and regulations of the country, and it is absolutely not allowed to add drugs that are prohibited by the country. Some farmers add ethanol, which is banned in aquatic products, to the feed to speed up the growth of fish. Although ethanol can be antibacterial and promote growth, long-term use will reduce the transport resistance of fish, increase the mortality rate during transport, and also reduce the quality of fish products, endangering human health.

Adding new additives such as probiotics, enzyme preparations, and Chinese herbal medicines to feed can significantly improve fish nutrition, promote fish growth, and reduce morbidity. Prebiotics are a concept opposite to antibiotics, which refer to active microorganisms or their cultures that can be directly fed to animals, and can prevent diseases, promote animal growth and improve feed utilization by regulating the microecological balance of the gastrointestinal tract of animals. Enzymes are proteins with biological activity. As feed additives, they are mainly hydrolytic enzymes to aid digestion. There are proteases, amylases, phytases, cellulases, etc., and there are also compound enzyme preparations containing various enzymes. The combined use of probiotics and enzyme preparations is more effective in production. The optimum combined addition level of grass carp feed is 0.52% to 0.66% of prebiotics and 0.20% to 0.21% of enzyme preparation; the optimum combined addition level of prebiotics to carp feed is 0.57% %～0.69%, enzyme preparation added 0.14%～0.18%. Our country is rich in Chinese herbal medicine resources, and the people of our country have accumulated rich experience in using Chinese herbal medicine to prevent and treat diseases for a long time. The Chinese herbal medicine is added into the feed to make the bait, which is easy to use, non-toxic and has no residue. For example, adding “three yellow powder” (the main ingredients are Scutellaria baicalensis, Coptis chinensis, Phellodendron phellodendri) to the feed can effectively prevent and treat the three diseases of grass carp. Adding pine needles, mugwort leaves, Poria cocos and other Chinese herbal medicines to fish feed can increase the survival rate and promote growth.