1. Effect of protein on immune function of fish and shrimp. Protein is an important nutrient for fish and shrimp, and it is an important constituent of cells, tissues and organs of the body. The normal growth of fish requires a sufficient amount of protein in the feed, which is easy to digest and absorb, and the proper ratio of various amino acids. When the fish intake of protein is insufficient, the growth is slow, the body's immune system is decreased, the tissue is renewed slowly, the wound healing ability is poor, and it is easy to get sick. Ingestion of too much protein, digestion and utilization of the protein will be excreted in the form of nitrogen, not only reduces the body's use of protein efficiency, but also increased the pressure of water quality management, but also easy to cause intestinal disease. Under relatively appropriate protein levels, amino acid balance not only results in faster growth of fish and shrimp, but also enhances its immunity.
2. Effects of fat on immune function of fish and shrimp. Fat, especially essential fatty acids, are important regulators of immune responses in fish and shrimp. The addition of essential fatty acids in the diet can improve the body's humoral immunity and cellular immunity, promote the production of cellular immune factors, and have an important effect on the mitogenic stimulation of lymphocyte proliferation, and can enhance the phagocytic ability of macrophages.
3. Effect of vitamins on immune function of fish and shrimp. (1) VC is a nutrient necessary for 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 influence on the humoral immune response and non-specific cellular immune response of fish and shrimp. Therefore, the addition of VC to fish and shrimp diets can enhance its immune function, and increase its resistance to disease and survival. VC is necessary for the normal immune response of fish and shrimp, but it does not act directly, but synergistically with some antioxidant substances (such as VE) and metal elements (such as copper and iron) that have defensive functions. (2) VE is also an important nutrient for fish and shrimp, its main function is antioxidant, to protect fat-soluble cell membrane and unsaturated fatty acids from oxidation, proper addition in feed can be used as immune-enhancing substance, strengthen cell phagocytosis, and strengthen the production of phagocytic cells. . (3) VA is necessary to maintain the normal function of the immune system of fish and shrimp. High levels of VA in feeds can increase lymphocyte phagocytosis and serum lysozyme and specific complement activity in fish and shrimp, and thus have an important impact on the immune function of fish and shrimp.
4. Effect of Mineral Elements on Immune Function of Fish and Shrimp Mineral elements such as iron, selenium, copper, zinc and other elements are important in the disease resistance and immune response of fish and shrimp, and they cannot be lacking in feed.
In summary, the nutrient composition of feed can not only affect the normal growth of fish and shrimp, but also affect the immunity of fish and shrimp. However, the relationship between the nutrition and immune factors of fish and shrimp and the interaction mechanism between them are still unclear. It is necessary to strengthen the study of the relationship between immune factors and nutrient substances in fish and shrimp, and provide a strong theoretical basis for aquaculture to promote Sustainable development of aquaculture.
The purpose of feeding fish to feed is to provide necessary nutritional requirements for keeping fish in good health, optimal growth, and optimum yield, and to minimize the waste brought to the environment for the best profit Pay a reasonable cost. The good nutritional quality and physical properties of the feed are the key to the fishery technology's achievement of production and economic goals.
Feed quality for fish farming must meet the following conditions:
1. Feed must be made granular or buoyant or dehydrated.
2. Only pelleted feeds that meet nutritional quality and physical properties can be used.
3. The feed used must be nutritionally complete, including complete vitamin and mineral premixes, as well as supplemental vitamin C and oils.
4. The protein content of feed is generally 32-36%. Feeds with high protein content are more expensive, but they are worth the expense, especially when the fish’s average body weight is ≥50 g.
5. The quality of the feed will decrease as the storage time increases. Feeds should be used within 6 weeks of manufacture, as the storage of vitamins and other nutrients will be lost and mold and other microbes will be destroyed.
Pond fish feed
1. The purpose of fish feed for pond fish is to feed the fish that meet the quality requirements with the prescribed amount and the number of feedings to obtain the best production results and benefits.
2. In order to balance the growth of fish and the feed coefficient, the optimum amount of feed for each feeding and daily feeding should be about 90% of the satiety of the fish; if the amount of feed is only 80% of the satiety, the feed The coefficient will be relatively low, but the growth will be slow; if the amount of feeding satisfies 100% of satiety, the growth will be good but the feed coefficient will be relatively large; if the amount of feed exceeds 100% of the fish's satiety, it will pollute the water quality and increase. Water quality management and useless feed expenses.
The amount of feed fed by the fish in the pond is mainly related to the water temperature and the average weight of the fish.
There are many ways to feed fodder, but here are some basic principles of advice:
a. The start of feeding (the first few days) was fed at a feeding rate of 3% (3% of the body weight of the fish). When the fish can actively ingest food, the fish will finish eating within 2 to 5 minutes.
b. Some fish, such as gully, usually feed in the evening, and should be trained to feed during the day. The feeding time is best from 8:00 am to 4:00 pm, or from 2 hours after dawn to 2 hours before dusk.
c. It is generally not necessary to feed twice or more times a day, but dividing the amount of feed each day into 2 to 3 servings and feeding it at intervals of 6 to 8 hours will make the fish grow faster under certain conditions. It will be lower, especially for smaller individuals and tilapia and mackerel.
d. Overfeeding should be strictly avoided. Overfeeding is marked by more than 10 minutes after feeding and the remaining feed is not consumed by the fish. When the existing stock of fish in the pond is close to the fish load, the problem of overfeeding should be given particular attention.
e. Each feed should be put into the immediate allocation of all the amount of feed, can not be divided into small batches by hand sprinkled one by one within a few minutes.
f. The amount of feed fed to fish every day is limited, because the pollution caused by metabolic waste has a negative impact on water quality.
Feed purchase and storage
Each time the feed is purchased, it should be able to meet the needs of 4-6 weeks. Feed should be stored in dry, ventilated, dark and cool warehouses to prevent infestation of animals and insects.
Feed coefficient
The feed coefficient is a measure of the efficiency of the fish producing nutrients with feed. It is often influenced by several factors including the quality of the feed, the amount of feed used, the type of fish, the size of the fish, and the quality of the water.
Feed high-quality pelleted diets of Nile tilapia, gully and squid from 15g to 500g, and add 1.0kg per body weight. The amount of feed should be between 1.2kg and 1.7kg. When the fish grows to a larger size, its feed coefficient increases.
Other issues to consider in feed and feeding
Nutrition (feed) is an important factor that needs attention in the management of fish farming. The quality of feed cannot be taken lightly. Special attention must be paid when buying and handling feeds, as feed and feeding expenses are the largest expense in fish production costs. The feeding behavior of fish is a sign of the health status of fish. If the fish eats actively, it means that the fish is in good health, and vice versa, indicating that the health condition is poor.
It is recommended not to use automatic feeders as this requires additional equipment expenses and usually the feed coefficient will be higher when using them. Fish farmers should constantly observe the status of fish, the overall behavior of fish feeding behavior and water environment, at least once a day. The amount of feed each time the fish is fed should be weighed and recorded. If the amount of feed eaten by the fish is difficult to weigh each day, the volumetric method (determined by the volume-weight conversion relationship) can be used to estimate the amount of feed, but whenever the brand and type of feed is changed, it should be re-determined.
The relationship between feed capacity and weight.
The sink pellet feed is cheaper than the float pellet feed and can be used for pond fish farming. However, buoyant pellet feeds are preferable because the use of buoyant pellet feed is not prone to waste, and it is also convenient for fish farmers to directly observe the feeding behavior of fish and other conditions.
If the price of the feed is directly related to the quality of the feed, then the cost of developing a season of fish with low-priced feeds will be higher than the expenditure of high prices. The relationship between the adjustment of the production performance and economic efficiency of feedstuffs and fish farming cannot be considered solely in terms of feed price.
The virus is composed of a nucleic acid molecule (DNA or RNA) with a protein consisting of non-cell morphology of the campal life of the living body. The general symptoms of viral infection are fever, headache, cough and other symptoms of systemic poisoning and viral host and invasion of tissues and organs leading to inflammatory symptoms caused by local symptoms (diarrhea, rash, liver function damage, etc.). Different symptoms of the different virus, some viruses can also damage the myocardium, causing viral myocarditis. There are two types of viral infections, mostly recessive infections (subclinical infections), and a few are dominant infections. Dominant infection can be divided into acute infection and persistent infection. There are many ways of antiviral infection, such as direct inhibition or killing of viruses, interference with virus adsorption, prevent viruses from penetrating cells, inhibit viral biosynthesis, inhibit viral release or enhance host antivirus capabilities. At present, there are several major types of antiviral drugs: Anti-Respiratory virus infection drugs, anti-immune virus drugs, anti-hepatitis virus drugs, anti-herpes virus drugs.
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