First, the nutritional needs of fish
(A) Proteins Proteins are the basic substances that constitute life, and are nitrogen-containing macromolecular compounds composed of amino acids. After the feed protein is ingested by the fish, it must be digested into amino acids in the digestive tract of the fish under the action of various digestive enzymes before it can be absorbed and utilized by the fish. The amino acid composition determines the quality of the protein. The essential amino acids of fish have been demonstrated to be lysine, methionine, phenylalanine, isoleucine, leucine, threonine, tryptophan, valine, arginine and histidine. Different kinds of fish require different proportions of essential amino acids in the protein. If the content and proportion of 10 essential amino acids in the feed protein are consistent with the needs of the fish, it is called balanced protein, if one or more essential amino acids Insufficient, it will limit the use of other amino acids. The lack of essential amino acids not only slows fish growth, but also induces certain diseases, such as the lack of methionine and tryptophan, which can cause cataracts in fish. Of the 10 essential amino acids, lysine and methionine are the limiting amino acids of fish. The requirements of fish for protein and amino acid content in feeds are influenced by the fish species, age, specifications, and ecological conditions of living waters. The protein and amino acid requirements of the main farmed fish in China are required. It can be seen from the table that carnivorous fish require high protein content in feed, generally more than 40%, omnivorous fish require lower, generally 30% to 40%, and herbivorous fish have a minimum of 30% or less. At the same time, it is related to the age of the fish. The growth of larvae and juveniles has high requirements for protein, and the slow growth of adult fish requires low protein.
(The above chart shows the table of the most suitable amount of feed protein for farmed fish (reference table (%)). The table shows the proportion of essential amino acids in protein of several kinds of fish feed (%).
(b) Fatty fat is the most important source of energy for fish. It produces 2.5 times more energy than eggs and carbohydrates. It is also a solvent for fat-soluble vitamins and a component of cells, especially energy. Supply fish essential fatty acids. Essential fatty acids cannot be synthesized in fish and must be provided by feed. Lack of it can cause fish metabolism disorders, nutritional disorders, growth stagnation, and frailty. The unsaturated fatty acids that are indispensable in fish are octadecadienoic acid (linoleic acid), octadecatrienoic acid (linolenic acid) and arachidonic acid (arachidonic acid).
Fish has a special ability to use fat, and its utilization rate can reach more than 90%. Different types of fish require different amounts of fat in the feed, and they are also affected by the environment. Generally, the fish feed should contain 4% to 18% of fat, and the fat content should be higher when the water temperature is high. On the contrary, it is lower, such as the temperature is lower than 23 ° C, carp feed fat content of 8% to 10%, the water temperature is higher than 23 ° C for 10% to 15%, but fat excess, such as excessive accumulation of fat in the liver, etc. can cause fish Physical discomfort. The content of fat in grass carp is controlled at 3%-8% in mid-month, 4%-15% for carp, 2%-5% for carp head, 5%-9% for Nile tilapia, other carnivorous fish The fat content in the feed is also between 5% and 8%.
(3) Sugar carbohydrates are a kind of nutrients necessary for fish growth. If the intake is insufficient, the utilization rate of feeds will decline, fish metabolism will be disordered, and the fish body will lose weight. Excessive intake exceeds the limits of the fish's ability to use sugar, and excess fat is synthesized. Excessive sugar intake over a long period of time can lead to fatty liver, weakening liver function, detoxification, and obesity. The use of carbohydrates by fish varies greatly depending on the type of fish and their diet. Such as grass carp due to long-term intake of sugary foods, so it has a strong ability to adapt to the sugar in the feed, feed sugar content of up to 40% or more; omnivorous fish in the dipping material sugar range of 30% to 40 %; Carnivorous fish have poor adaptability to sugars, and generally require that the content of sugars in feed is below 20%; the fish's ability to use sugar varies with the type of sugar, with the highest monosaccharide, followed by It is maltose, galactose, sucrose, dextrin and starch. The worst utilization rates are hemicellulose and cellulose. Since the macromolecule cellulose can hardly be digested and absorbed by most fish, the crude fiber content in the general fish feed is limited to a certain range of solid content, and to the herbivorous grass carp and the head louse, the crude fiber content in the feed is limited. Should not exceed 17%, omnivorous carp should not exceed 12%, while carnivorous fish should not exceed 8%.
(D) Vitamins Vitamins are essential special nutrients in the metabolism of fish. It is neither a material that constitutes the body structure nor energy, but it participates in the regulation of metabolism, controls the growth and development of fish, and improves the resistance of the body. Vitamins are divided into fat-soluble vitamins and water-soluble vitamins. Vitamin A, Vitamin D, Vitamin E, and Vitamin K are fat-soluble vitamins that are absorbed along with fat and can be stored in fish fat and cannot be synthesized in fish. Vitamin B1, Vitamin B2, Vitamin B. Pantothenic acid, niacin, biotin, folic acid, vitamin B, choline, inositol, and vitamin C are water-soluble vitamins. They cannot be stored in the body and therefore need to be continuously supplied from the feed. Vitamins are rarely found in animals but are essential. Fish lacking vitamins can suffer from various diseases. Lack of vitamin A, will reduce the resistance to infectious diseases, resulting in edema, renal hemorrhage, affecting growth; lack of vitamin D3, affect fish bone calcification, and cause vitamin A, unsaturated fatty acid oxidation, resulting in other diseases; lack of vitamins K, blood stasis is not easy to coagulate, produce internal hemorrhage; lack of vitamin B1, resulting in fish deformity, neuritis, digestive system disorders; lack of vitamin B6, resulting in edema, dermatitis, eyeball outbreaks, movement disorders, weight gain slow down; lack of vitamin C effects Skeletal development and growth; lack of niacin, anemia, gastrointestinal disorders, impaired nerve function; lack of choline, impaired fat metabolism, suffering from fatty liver.
(5) Inorganic salts Inorganic salts are the main components of fish bodies, and they are also the catalysts of enzyme systems. They exist as ions in body fluids. They are related to osmotic pressure and pH adjustment, and they have physiological functions that promote biological growth. According to the different content of inorganic salts in the body, it can be divided into two major categories: constant elements and trace elements. Calcium, phosphorus, sodium, chlorine, magnesium, potassium, sulfur, etc. account for more than 0.01% of animal body weight in animals and are called constant elements. Iron, copper, zinc, iodine, manganese, fluorine, chromium, molybdenum, selenium, etc. account for less than 0.01% of animal body weight in animals and are called trace elements. Freshwater fish can absorb inorganic salts in water through body surface, limpets, fins, etc., but the amount absorbed is very limited and must be supplemented from the feed.
When the inorganic salt in the feed is lacking, the fish will have metabolic disorders and thus affect normal growth and development. Absence of calcium, impaired bone development; lack of phosphorus, carp cranium and lid defect; lack of potassium, osmotic pressure in fish lose balance; lack of magnesium, skeletal system and glucose metabolism, protein metabolism are affected; lack of manganese, skeletal system and metabolism are affected Lack of iodine, goiter, basal metabolism; lack of cobalt, poor appetite for fish, growth stopped; lack of molybdenum, embryonic development blocked; lack of selenium, sexual function affected. (The following table shows the amount of inorganic salt required per kilogram of feed for fish)
Second, the fish feed raw materials Fish feed raw material feed is the material basis for animal husbandry, and most of its raw materials come from plants, some from animals, inorganic salts and microorganisms. According to the International Feed Classification Act, feed ingredients can be divided into eight categories:
Roughage 100000 crude fiber accounts for more than 18% of the dry weight of feeds, such as hay, crop straw.
Green feed 200,000 Green plants, leaves and non-amyloid rhizomes, fruits, natural moisture content of more than 60%, regardless of the crude protein and crude fiber content after its folding.
Silage 300,000 Silage prepared from fresh natural plant feed, and silage with appropriate amount of bran or other additives, and low moisture silage with moisture at 45% to 55% Energy feed 400,000 feed dry matter Crude protein less than 20%, crude fiber less than 18%, such as cereals, bran, grass seeds, seed and starchy root fruits and fruits.
Protein feed 500000 Crude protein in feed dry matter is more than 20%, crude fiber is less than 18%, such as animal feed, legume cake and other inorganic salt feed 600,000 including industrial synthetic, natural single inorganic salt feed, many Inorganic salt, mixed inorganic salt feed and inorganic salt additive of the loading body or diluent vitamin feed 700,000 refers to a single vitamin or compound vitamin synthesized or extracted by industry, but does not include a natural feed containing a certain amount of vitamins.
Non-nutritional 800,000 Does not include all additives such as mineral elements, vitamins, amino acids, and other nutrients. It does not provide nutrients to animals, but helps to digest nutrients, stimulate animal growth, protect feed quality, and improve Feed utilization and the role of aquatic product quality substances.
Third, the fish compound feed The so-called fish compound feed, refers to a variety of raw materials in accordance with the nutritional needs of fish, according to a certain proportion of uniform mixing, processed into a certain shape of the feed product. The formula is scientific and reasonable, nutrition is comprehensive, and it fully meets the needs of fish for the growth of compound feed, and is known as full-price compound feed for fish.
(1) The type of compound feed can be divided into six types: powdered feed, dough-shaped feed, crushed granular feed, biscuit-like feed, granular feed, and micro-feed according to the form of the feed. According to the water content and density of pellet feed, it can be divided into hard pellet feed, soft pellet feed, expanded pellet feed and micro pellet feed. According to the ups and downs of the feed in the water, it is divided into floating feed, semi-floating feed and sink feed.
In accordance with the nutrients of feed can be divided into full price feed, concentrated feed, premixed feed and additive four.
In accordance with the breeding objects can be divided into four kinds of fry opening materials, feed for fish species, adult fish feed and fish feed.
According to the form classification, the main types are described as follows:
(1) Powdered feed Powdered feed is made by crushing raw materials to a certain degree and mixing them evenly. Due to the different water content in the feed, there are differences in the form of powder, paste, mash, and dough. Powdered feeds are suitable for rearing fry, small fingerlings, and fish that feed on plankton. The powdered feed is processed, added with adhesives, starch and grease sprays, and kneaded to form dough or pods. It can be used for squid, shrimp, crab, clam and other valuable carnivorous fish.
(2) Pellet feed feed raw materials are first crushed (or mixed first), and then fully stirred and mixed. Adding water and additives, granulated feeds processed in pellet machines are collectively called pellet feeds and can be divided into the following four types:
1. Hard pellet feed has a moisture content of less than 13%, particle density greater than 1.3 g/m3, and sinking. Steam tempering above 80 °C, rigid, diameter 1 ~ 8 mm, length of 1 ~ 2 times the diameter. It is suitable for cultivation of cockroaches, cockroaches, cockroaches, cockroaches, grass carp, herring, group head cockroach, tilapia and other varieties.
2. Soft pellet feed has a water content of 20% to 30%, particle density of 1 to 1.3 g/cm3, softness, diameter of 1 to 8 mm, noodle or granular feed. No steam is added during the molding process, but 40% to 50% of water is added, and the molding is dried and dehydrated. The current species cultivated in China, especially herbivorous, carnivorous, or meat-eating omnivorous fish, prefer this feed, such as grass carp and catfish; carp and carp. The disadvantage of soft pellet feed is that it has a large amount of moisture, is susceptible to mildew, and is not easy to store and transport.
3. Extruded pellets have a moisture content less than that of hard pellets after molding, and a particle density of about 0.6 g/cm3, which is a buoyant foamy granule. Can be floating on the water for 12 to 24 hours without dissolution, nutrient loss is small, but also can directly observe the fish eating conditions, to facilitate accurate control of feeding, so the feed utilization rate is higher. Japan is mainly used to raise koi fish, lionfish and real fish.
4. Micro pellet feed Micro pellet feed is a generic term for novel feeds with diameters up to 500 microns and as small as 8 microns. They are often used as a substitute for plankton, known as artificial plankton. Feeding newly hatched fry, shrimp, crabs and shellfish is also known as open feed.
(II) Formulating principles of compound feed
(I) The design of feed formulations in accordance with the needs of cultured fish cultures must be based on the nutritional needs of fish and the nutritional value of feed. This is the first principle. Due to the different species, age, weight, habits, physiological conditions and water quality environment of farmed fish, the requirements and quality requirements for various nutrients are different. The recipe must first meet the fish's requirements for feed energy and maintain the optimal ratio of protein to energy. Secondly, it is necessary to focus on the ratio of protein and amino acid content of feed to meet the nutritional standards. Once again, the characteristics of the digestive tract of the fish should be considered. Since the digestive tract of the fish is simple and primitive, it is difficult to digest and absorb crude fiber, so it is necessary to control the content of crude fiber in the feed to the lowest range, generally controlled at 3% to 17%, and sugar control. At 20% to 45%.
(2) Pacifiers' palatability and digestibility Based on the digestive physiology, feeding habits and preferences of different fishes, select suitable feeds. Such as blood protein contains up to 83.3%, but digestible protein is only 19.3%; meat and bone meal protein is only 48.6%, but because its digestibility is 75%, digestible protein is 36.5%, high bleeding Powder twice. Another example is the poor palatability of rapeseed cake, which may lead to insufficient food intake, resulting in feed wastage.
(3) Protein and Amino Acids in Balanced Formula Fish ingredient formulations need to consider the balance of protein amino acids, that is, multiple raw materials must be selected to complement each other to meet the requirements of the nutritional standards.
(D) reduce the cost of raw materials In addition to considering the nutritional characteristics of raw materials, we must also consider the economic factors, according to local conditions, in order to obtain the greatest economic benefits.
(5) Selection of appropriate additives The raw materials for compound feeds are mainly animal raw materials and vegetable raw materials. In order to improve nutrient composition and feed efficiency, it is also necessary to consider adding mixed vitamins, mixed inorganic salts, colorants, attractants, and stickies. Mixtures and other additives.
Fourth, the design formula of the feed formula with feed needs to be calculated, there are many methods, such as box method, simultaneous equation method, nutrient content calculation method, linear programming and electronic calculation. Machine matching method, trial word balance method. The most commonly used is the square method, also called the diagonal method. Here are some examples:
If you want to use a protein with a protein content of 17%, 40% of the secondary powder and bean cake with a protein content of 30%, the calculation method is as follows:
Secondary powder 17 40-30=10
30
Bean cake 40 30-17=13
The proportion of secondary powder should be: 10/(13+10)=43.48%
The proportion of soybean cake should be: 13/(13+10)=56.52%
Checking: 43.48%X17%+56.52%X40%=30%
(A) Proteins Proteins are the basic substances that constitute life, and are nitrogen-containing macromolecular compounds composed of amino acids. After the feed protein is ingested by the fish, it must be digested into amino acids in the digestive tract of the fish under the action of various digestive enzymes before it can be absorbed and utilized by the fish. The amino acid composition determines the quality of the protein. The essential amino acids of fish have been demonstrated to be lysine, methionine, phenylalanine, isoleucine, leucine, threonine, tryptophan, valine, arginine and histidine. Different kinds of fish require different proportions of essential amino acids in the protein. If the content and proportion of 10 essential amino acids in the feed protein are consistent with the needs of the fish, it is called balanced protein, if one or more essential amino acids Insufficient, it will limit the use of other amino acids. The lack of essential amino acids not only slows fish growth, but also induces certain diseases, such as the lack of methionine and tryptophan, which can cause cataracts in fish. Of the 10 essential amino acids, lysine and methionine are the limiting amino acids of fish. The requirements of fish for protein and amino acid content in feeds are influenced by the fish species, age, specifications, and ecological conditions of living waters. The protein and amino acid requirements of the main farmed fish in China are required. It can be seen from the table that carnivorous fish require high protein content in feed, generally more than 40%, omnivorous fish require lower, generally 30% to 40%, and herbivorous fish have a minimum of 30% or less. At the same time, it is related to the age of the fish. The growth of larvae and juveniles has high requirements for protein, and the slow growth of adult fish requires low protein.
(The above chart shows the table of the most suitable amount of feed protein for farmed fish (reference table (%)). The table shows the proportion of essential amino acids in protein of several kinds of fish feed (%).
(b) Fatty fat is the most important source of energy for fish. It produces 2.5 times more energy than eggs and carbohydrates. It is also a solvent for fat-soluble vitamins and a component of cells, especially energy. Supply fish essential fatty acids. Essential fatty acids cannot be synthesized in fish and must be provided by feed. Lack of it can cause fish metabolism disorders, nutritional disorders, growth stagnation, and frailty. The unsaturated fatty acids that are indispensable in fish are octadecadienoic acid (linoleic acid), octadecatrienoic acid (linolenic acid) and arachidonic acid (arachidonic acid).
Fish has a special ability to use fat, and its utilization rate can reach more than 90%. Different types of fish require different amounts of fat in the feed, and they are also affected by the environment. Generally, the fish feed should contain 4% to 18% of fat, and the fat content should be higher when the water temperature is high. On the contrary, it is lower, such as the temperature is lower than 23 ° C, carp feed fat content of 8% to 10%, the water temperature is higher than 23 ° C for 10% to 15%, but fat excess, such as excessive accumulation of fat in the liver, etc. can cause fish Physical discomfort. The content of fat in grass carp is controlled at 3%-8% in mid-month, 4%-15% for carp, 2%-5% for carp head, 5%-9% for Nile tilapia, other carnivorous fish The fat content in the feed is also between 5% and 8%.
(3) Sugar carbohydrates are a kind of nutrients necessary for fish growth. If the intake is insufficient, the utilization rate of feeds will decline, fish metabolism will be disordered, and the fish body will lose weight. Excessive intake exceeds the limits of the fish's ability to use sugar, and excess fat is synthesized. Excessive sugar intake over a long period of time can lead to fatty liver, weakening liver function, detoxification, and obesity. The use of carbohydrates by fish varies greatly depending on the type of fish and their diet. Such as grass carp due to long-term intake of sugary foods, so it has a strong ability to adapt to the sugar in the feed, feed sugar content of up to 40% or more; omnivorous fish in the dipping material sugar range of 30% to 40 %; Carnivorous fish have poor adaptability to sugars, and generally require that the content of sugars in feed is below 20%; the fish's ability to use sugar varies with the type of sugar, with the highest monosaccharide, followed by It is maltose, galactose, sucrose, dextrin and starch. The worst utilization rates are hemicellulose and cellulose. Since the macromolecule cellulose can hardly be digested and absorbed by most fish, the crude fiber content in the general fish feed is limited to a certain range of solid content, and to the herbivorous grass carp and the head louse, the crude fiber content in the feed is limited. Should not exceed 17%, omnivorous carp should not exceed 12%, while carnivorous fish should not exceed 8%.
(D) Vitamins Vitamins are essential special nutrients in the metabolism of fish. It is neither a material that constitutes the body structure nor energy, but it participates in the regulation of metabolism, controls the growth and development of fish, and improves the resistance of the body. Vitamins are divided into fat-soluble vitamins and water-soluble vitamins. Vitamin A, Vitamin D, Vitamin E, and Vitamin K are fat-soluble vitamins that are absorbed along with fat and can be stored in fish fat and cannot be synthesized in fish. Vitamin B1, Vitamin B2, Vitamin B. Pantothenic acid, niacin, biotin, folic acid, vitamin B, choline, inositol, and vitamin C are water-soluble vitamins. They cannot be stored in the body and therefore need to be continuously supplied from the feed. Vitamins are rarely found in animals but are essential. Fish lacking vitamins can suffer from various diseases. Lack of vitamin A, will reduce the resistance to infectious diseases, resulting in edema, renal hemorrhage, affecting growth; lack of vitamin D3, affect fish bone calcification, and cause vitamin A, unsaturated fatty acid oxidation, resulting in other diseases; lack of vitamins K, blood stasis is not easy to coagulate, produce internal hemorrhage; lack of vitamin B1, resulting in fish deformity, neuritis, digestive system disorders; lack of vitamin B6, resulting in edema, dermatitis, eyeball outbreaks, movement disorders, weight gain slow down; lack of vitamin C effects Skeletal development and growth; lack of niacin, anemia, gastrointestinal disorders, impaired nerve function; lack of choline, impaired fat metabolism, suffering from fatty liver.
(5) Inorganic salts Inorganic salts are the main components of fish bodies, and they are also the catalysts of enzyme systems. They exist as ions in body fluids. They are related to osmotic pressure and pH adjustment, and they have physiological functions that promote biological growth. According to the different content of inorganic salts in the body, it can be divided into two major categories: constant elements and trace elements. Calcium, phosphorus, sodium, chlorine, magnesium, potassium, sulfur, etc. account for more than 0.01% of animal body weight in animals and are called constant elements. Iron, copper, zinc, iodine, manganese, fluorine, chromium, molybdenum, selenium, etc. account for less than 0.01% of animal body weight in animals and are called trace elements. Freshwater fish can absorb inorganic salts in water through body surface, limpets, fins, etc., but the amount absorbed is very limited and must be supplemented from the feed.
When the inorganic salt in the feed is lacking, the fish will have metabolic disorders and thus affect normal growth and development. Absence of calcium, impaired bone development; lack of phosphorus, carp cranium and lid defect; lack of potassium, osmotic pressure in fish lose balance; lack of magnesium, skeletal system and glucose metabolism, protein metabolism are affected; lack of manganese, skeletal system and metabolism are affected Lack of iodine, goiter, basal metabolism; lack of cobalt, poor appetite for fish, growth stopped; lack of molybdenum, embryonic development blocked; lack of selenium, sexual function affected. (The following table shows the amount of inorganic salt required per kilogram of feed for fish)
Second, the fish feed raw materials Fish feed raw material feed is the material basis for animal husbandry, and most of its raw materials come from plants, some from animals, inorganic salts and microorganisms. According to the International Feed Classification Act, feed ingredients can be divided into eight categories:
Roughage 100000 crude fiber accounts for more than 18% of the dry weight of feeds, such as hay, crop straw.
Green feed 200,000 Green plants, leaves and non-amyloid rhizomes, fruits, natural moisture content of more than 60%, regardless of the crude protein and crude fiber content after its folding.
Silage 300,000 Silage prepared from fresh natural plant feed, and silage with appropriate amount of bran or other additives, and low moisture silage with moisture at 45% to 55% Energy feed 400,000 feed dry matter Crude protein less than 20%, crude fiber less than 18%, such as cereals, bran, grass seeds, seed and starchy root fruits and fruits.
Protein feed 500000 Crude protein in feed dry matter is more than 20%, crude fiber is less than 18%, such as animal feed, legume cake and other inorganic salt feed 600,000 including industrial synthetic, natural single inorganic salt feed, many Inorganic salt, mixed inorganic salt feed and inorganic salt additive of the loading body or diluent vitamin feed 700,000 refers to a single vitamin or compound vitamin synthesized or extracted by industry, but does not include a natural feed containing a certain amount of vitamins.
Non-nutritional 800,000 Does not include all additives such as mineral elements, vitamins, amino acids, and other nutrients. It does not provide nutrients to animals, but helps to digest nutrients, stimulate animal growth, protect feed quality, and improve Feed utilization and the role of aquatic product quality substances.
Third, the fish compound feed The so-called fish compound feed, refers to a variety of raw materials in accordance with the nutritional needs of fish, according to a certain proportion of uniform mixing, processed into a certain shape of the feed product. The formula is scientific and reasonable, nutrition is comprehensive, and it fully meets the needs of fish for the growth of compound feed, and is known as full-price compound feed for fish.
(1) The type of compound feed can be divided into six types: powdered feed, dough-shaped feed, crushed granular feed, biscuit-like feed, granular feed, and micro-feed according to the form of the feed. According to the water content and density of pellet feed, it can be divided into hard pellet feed, soft pellet feed, expanded pellet feed and micro pellet feed. According to the ups and downs of the feed in the water, it is divided into floating feed, semi-floating feed and sink feed.
In accordance with the nutrients of feed can be divided into full price feed, concentrated feed, premixed feed and additive four.
In accordance with the breeding objects can be divided into four kinds of fry opening materials, feed for fish species, adult fish feed and fish feed.
According to the form classification, the main types are described as follows:
(1) Powdered feed Powdered feed is made by crushing raw materials to a certain degree and mixing them evenly. Due to the different water content in the feed, there are differences in the form of powder, paste, mash, and dough. Powdered feeds are suitable for rearing fry, small fingerlings, and fish that feed on plankton. The powdered feed is processed, added with adhesives, starch and grease sprays, and kneaded to form dough or pods. It can be used for squid, shrimp, crab, clam and other valuable carnivorous fish.
(2) Pellet feed feed raw materials are first crushed (or mixed first), and then fully stirred and mixed. Adding water and additives, granulated feeds processed in pellet machines are collectively called pellet feeds and can be divided into the following four types:
1. Hard pellet feed has a moisture content of less than 13%, particle density greater than 1.3 g/m3, and sinking. Steam tempering above 80 °C, rigid, diameter 1 ~ 8 mm, length of 1 ~ 2 times the diameter. It is suitable for cultivation of cockroaches, cockroaches, cockroaches, cockroaches, grass carp, herring, group head cockroach, tilapia and other varieties.
2. Soft pellet feed has a water content of 20% to 30%, particle density of 1 to 1.3 g/cm3, softness, diameter of 1 to 8 mm, noodle or granular feed. No steam is added during the molding process, but 40% to 50% of water is added, and the molding is dried and dehydrated. The current species cultivated in China, especially herbivorous, carnivorous, or meat-eating omnivorous fish, prefer this feed, such as grass carp and catfish; carp and carp. The disadvantage of soft pellet feed is that it has a large amount of moisture, is susceptible to mildew, and is not easy to store and transport.
3. Extruded pellets have a moisture content less than that of hard pellets after molding, and a particle density of about 0.6 g/cm3, which is a buoyant foamy granule. Can be floating on the water for 12 to 24 hours without dissolution, nutrient loss is small, but also can directly observe the fish eating conditions, to facilitate accurate control of feeding, so the feed utilization rate is higher. Japan is mainly used to raise koi fish, lionfish and real fish.
4. Micro pellet feed Micro pellet feed is a generic term for novel feeds with diameters up to 500 microns and as small as 8 microns. They are often used as a substitute for plankton, known as artificial plankton. Feeding newly hatched fry, shrimp, crabs and shellfish is also known as open feed.
(II) Formulating principles of compound feed
(I) The design of feed formulations in accordance with the needs of cultured fish cultures must be based on the nutritional needs of fish and the nutritional value of feed. This is the first principle. Due to the different species, age, weight, habits, physiological conditions and water quality environment of farmed fish, the requirements and quality requirements for various nutrients are different. The recipe must first meet the fish's requirements for feed energy and maintain the optimal ratio of protein to energy. Secondly, it is necessary to focus on the ratio of protein and amino acid content of feed to meet the nutritional standards. Once again, the characteristics of the digestive tract of the fish should be considered. Since the digestive tract of the fish is simple and primitive, it is difficult to digest and absorb crude fiber, so it is necessary to control the content of crude fiber in the feed to the lowest range, generally controlled at 3% to 17%, and sugar control. At 20% to 45%.
(2) Pacifiers' palatability and digestibility Based on the digestive physiology, feeding habits and preferences of different fishes, select suitable feeds. Such as blood protein contains up to 83.3%, but digestible protein is only 19.3%; meat and bone meal protein is only 48.6%, but because its digestibility is 75%, digestible protein is 36.5%, high bleeding Powder twice. Another example is the poor palatability of rapeseed cake, which may lead to insufficient food intake, resulting in feed wastage.
(3) Protein and Amino Acids in Balanced Formula Fish ingredient formulations need to consider the balance of protein amino acids, that is, multiple raw materials must be selected to complement each other to meet the requirements of the nutritional standards.
(D) reduce the cost of raw materials In addition to considering the nutritional characteristics of raw materials, we must also consider the economic factors, according to local conditions, in order to obtain the greatest economic benefits.
(5) Selection of appropriate additives The raw materials for compound feeds are mainly animal raw materials and vegetable raw materials. In order to improve nutrient composition and feed efficiency, it is also necessary to consider adding mixed vitamins, mixed inorganic salts, colorants, attractants, and stickies. Mixtures and other additives.
Fourth, the design formula of the feed formula with feed needs to be calculated, there are many methods, such as box method, simultaneous equation method, nutrient content calculation method, linear programming and electronic calculation. Machine matching method, trial word balance method. The most commonly used is the square method, also called the diagonal method. Here are some examples:
If you want to use a protein with a protein content of 17%, 40% of the secondary powder and bean cake with a protein content of 30%, the calculation method is as follows:
Secondary powder 17 40-30=10
30
Bean cake 40 30-17=13
The proportion of secondary powder should be: 10/(13+10)=43.48%
The proportion of soybean cake should be: 13/(13+10)=56.52%
Checking: 43.48%X17%+56.52%X40%=30%
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