1.The feeding and selling of Tilapia
The purchase and sale of tilapia are mainly divided into four grades, which are the average tail weight below 0.5kg, 0.5～0.8kg, 0.8～1.1kg, 1.1kg and above, and correspondingly there are four grades of product prices.If the breeding conditions are poor, the main species of tilapia should not exceed 1,000 fish/mu.
2.the advantages of floating fish feed pellet
this feed is more easier for fish`s digest, and can easily observe the food consumption of frog ,fish without causing waste and pollution of feed. The material effectively kills harmful bacteria such as Escherichia coli and Salmonella by high temperature and high pressure, ensures the hygiene of the feed, facilitates protein denaturation absorption and starch gelatinization, and is easy for fish and animal to absorb.
Generally, puffed floating fish feed is used to save 8%-15% of feed compared to powdered or sinking feed.
3.The influence of protein on the immune function of fish and shrimp
Protein is an important nutrient for fish and shrimp to survive, and an important component of the body's cells, tissues and organs. The normal growth of fish requires a sufficient amount of protein in the feed, which is easy to digest and absorb, and a suitable ratio of various amino acids. When the fish intake of protein is insufficient, the growth is slow, the body's immunity is reduced, the tissue renewal is slow, the wound healing ability is poor, and it is easy to get sick. If you eat too much protein, the protein that cannot be digested and used will be excreted in the form of nitrogen, which not only reduces the body's utilization efficiency of protein, but also increases the pressure of water quality management, and it is also easy to cause intestinal diseases. Under the condition of relatively suitable protein level, the balance of amino acids will not only make fish and shrimp obtain a faster growth rate, but also their immunity will be enhanced.
4.The effect of fat on the immune function of fish and shrimp
Fats, especially essential fatty acids, are important regulators of fish and shrimp immune responses. Adding essential fatty acids to the diet can improve the humoral and cellular immunity of the animal's body, promote the production of cellular immune factors, have an important impact on the proliferation of lymphocytes stimulated by mitosis, and can enhance the phagocytic ability of macrophages.
5.The effect of vitamins on the immune function of fish and shrimp.
⑴VC is a nutrient necessary for the normal growth and maintenance of normal physiological functions of fish and shrimp, and many fish and shrimp cannot be synthesized and must be obtained from the diet. VC has a certain effect on the humoral immune response and non-specific cellular immune response of fish and shrimp. Therefore, adding VC to the fish and shrimp diet can enhance its immune function, improve its disease resistance and survival rate. VC is necessary for the normal immune response of fish and shrimps, but it does not act directly, but cooperates with some antioxidant substances (such as VE) and metal elements (such as copper and iron) that have defensive functions on the body.
⑵VE is also an important nutrient for fish and shrimp. Its main function is antioxidant, to protect fat-soluble cell membranes and unsaturated fatty acids from oxidation. Appropriate addition of VE in feed can be used as an immune-enhancing substance to strengthen the phagocytosis of cells and the production of phagocytes. . ⑶VA is necessary to maintain the normal function of the fish and shrimp immune system. The high level of VA in the feed can improve the phagocytic ability of lymphocytes in fish and shrimp and the vitality of serum lysozyme and specific complement, thereby having an important impact on the immune function of fish and shrimp.
6.Feed quality conditions for fish farming
1.The feed must be made into pellets or floating or sinking.
2.Only pellet feeds that meet the nutritional quality and physical properties can be used.
3. The feed used must be nutritionally complete, including a complete premix of vitamins and minerals, as well as supplemented vitamin C and oil
4. The protein content of feed is generally 32-36%. Feeds with high protein content are more expensive, but it is worth the expense, especially when the average weight of the fish is ≥50 grams.
5. The quality of feed will decrease with the extension of storage time. The feed should be used up within 6 weeks after manufacture, because the storage time is too long, its vitamins and other nutrients will be lost, and it will be destroyed by mold and other microorganisms.
Feed coefficient is an evaluation standard for the efficiency of fish production with feed nutrients. It is often affected by several factors, including the quality of feed, the amount of feed, the type of fish, the size of the fish and the water quality. Feed the high-quality pellet feed of Nile tilapia, channel catfish and carp from 15 grams to 500 grams. For every 1.0 kg increase in body weight, the amount of feed should be 1.2 kg-1.7 kg. When the fish grows to a larger size, its feed coefficient will increase.