Nutritional requirements of animals
There are thousands of plants on the earth, and various byproducts and micro-minerals are abundant, providing sufficient nutritional supplements for the growth and development of animals. From the perspective of nutrition, we can divide the types of animal needs into the following six categories:
Category 1: Roughage
Including straw and other hay, leaves, grass and silage
Hay is a type of feed with a moisture content of less than 45% and a crude fiber content of less than 18; including corn straw, wheat straw, oat straw, alfalfa hay, cowpea hay, soybean hay, Lespedeza hay harvested in full bloom, astragalus hay, sweet clover hay, arrowroot hay, dandelion (early flowering) hay, rapeseed hay harvested in early flowering, etc. This type of feed can generally only be used by herbivores. Its large size can not only satisfy the animal’s sense of fullness, but also stimulate the normal gastrointestinal peristalsis and reverse rumination function of the animal.
Leaves include dried locust leaves, dried elm leaves, banyan leaves, bauhinia leaves, willow leaves, poplar leaves, albizzia leaves, poplar leaves, birch leaves, cypress leaves, oak leaves, toon leaves, jujube leaves, banana leaves, mulberry leaves, wolfberry leaves, sea buckthorn leaves, etc.
Green fodder refers to a kind of feed with a natural moisture content of more than 60%, rich in chlorophyll, and in a green state. Such as meadow grass, brome, meadow fescue, orchard grass, ryegrass, green wheat grass, sheep grass from leaf peak to early flowering period, clover in early flowering period, Lespedeza, fresh rapeseed, Sudan grass, green wheat, fresh glutinous corn stalks that are on the market early, whole corn stalks for silage, fresh branches and leaves, various leafy crops, aquatic plants, etc.
Green fodder has tender fiber, is easy to digest, has good palatability, and well-preserved minerals and vitamins. It is the favorite food of animals. However, the water content of green fodder is too high, which leads to a decrease in the concentration of nutrients. Animals need to eat a lot to meet the nutritional supply; secondly, too high a water content will also cause the digestive juice to be diluted, the contents to stay in the gastrointestinal tract for a short time, and the digestion and absorption level of nutrients will be reduced. If the water content of the feed is too high, it is easy to cause diarrhea.
Silage refers to fresh green fodder cut into short pieces and stored in a sealed pit or container for a period of time. After the lactic acid bacteria in the sealed pit or container multiply and produce a large amount of lactic acid to kill the bacteria in the fodder, the silage can be stored for a long time without deterioration.
Silage preserves the vitamins and minerals in green fodder almost perfectly, and also has a sweet and sour flavor, which improves the palatability of animals. However, the water content of silage is too high, and silage is generally mixed with hay feed.
Feeding silage for a long time will lower the pH value of the rumen of cattle and sheep, especially in the current high-concentrate feeding mode, which will cause some diseases. Therefore, if silage is used for a long time, baking soda and rumen regulating products must be added to the diet to neutralize the acid.
Secondly, silage is very easy to get moldy when it is stored and exposed to oxygen. These moldy silages can cause diarrhea in animals at the least and poisoning and death in animals at the worst. Therefore, the silage must be used up as soon as possible after it is taken.
Category 2: Energy feed
Energy feed refers to feed with a crude fiber content of less than 18% and a crude protein content of less than 20% in absolute dry matter, and a digestible energy of more than 10.465 megajoules per kilogram of feed dry matter. Feeds with a digestible energy value of more than 12.558 megajoules are high-energy feeds, and feeds with a digestible energy value of less than 12.558 megajoules are low-energy feeds. This type of feed generally accounts for 50%-70% of the animal’s daily diet and is the absolute main feed, which can provide energy for animals. Energy feed includes two categories: plant energy feed and oil energy feed.
Plant energy feed
Cereal feed
● Corn
Corn is a high-energy feed and the main energy feed in my country, known as the “king of feed”. Corn contains high usable energy for two main reasons: ① Corn contains up to 72% nitrogen-free liquid extract, of which the main component is easily digestible starch, while crude fiber is only 2%. ② The fat content is high, generally 3.1-4.5%, which is twice that of wheat or barley. Corn contains a high amount of linoleic acid, which is an essential fatty acid. Animals lacking linoleic acid can lead to poor growth, skin lesions, and decreased fertility. If corn accounts for more than 50% of the compound feed, it can meet the animal’s need for linoleic acid. The disadvantages of corn are low protein content and unbalanced amino acid composition. Corn contains about 8.5% protein, which is lower than that of wheat, barley and other grains. The content of lysine, methionine and tryptophan is insufficient. Compound feeds based on corn must be matched with cakes and animal protein.
● barley
Barley comes in two types: hulled and unhulled. The usual barley is hulled barley, which has a metabolic energy of about 11.30 MJ/kg, while the metabolic energy of unhulled barley is about 11.72 MJ/kg. Barley has good palatability and contains about 5% crude fiber, which can promote gastrointestinal motility in animals and maintain normal digestive function. Pigs, poultry, and herbivores all like to eat it. The linoleic acid and vitamin content of barley are both low. Most of the barley produced in my country is used as a raw material for beer brewing, so the amount used as feed is relatively small. If the price is reasonable, barley should be selected to replace part of corn when preparing feed.
● wheat
Wheat is the staple food of the Chinese people. It was rarely used as feed in the past, but in recent years, the price of wheat in some parts of my country is lower than that of corn. Therefore, wheat has been increasingly used as feed. The metabolic energy level of wheat is about 12.97 trillion, and the crude fat content is low, only about 1.7%. However, the crude protein content of wheat is relatively high, and lysine and threonine are obviously insufficient. The wheat seed coat has high calcium and magnesium content.
● Paddy and brown rice
Rice is the most important grain in my country, accounting for about half of my country’s grain output. Rice is processed into rice as food for humans, while some areas in southern my country where corn is insufficient often use rice, brown rice, broken rice and old rice as feed. The metabolizable energy value of rice is low, only 10.5-10.9 MJ/kg. The only difference between rice and brown rice is the presence or absence of rice husk. Rice husk is the least nutritious of the grain skin, or mainly lignin and silicate, and rice husk accounts for about 20-25% of rice. Since rice husk is difficult to digest, it is not suitable to use rice as feed. Rice is husked to brown rice, and the metabolizable energy of brown rice is about 14 MJ/kg, which is equivalent to corn. The protein content and amino acid composition of brown rice are equivalent to those of corn and other grains. Brown rice contains about 2% fat, less minerals, and about 70% of the phosphorus contained is phytic acid phosphorus, with a slightly lower utilization rate. The content of B vitamins is high, but beta-carotene is very low.
Bran
Rice bran is one of the by-products of rice production. The rice bran cake used as feed in my country belongs to defatted rice bran products. The metabolic energy level of rice bran is relatively high, at 11.3 MJ/kg, and the crude fiber content is about 9%; the crude protein is relatively low, at about 12%, but the crude fat content is high, at 15%, which is 4 times that of corn. The crude fat of rice bran contains a lot of unsaturated fatty acids, which are easily oxidized during long-term storage, so it is best to feed it fresh. Sour and moldy rice bran can poison animals, leading to severe diarrhea and even death. Rice bran is rich in beta vitamins, but less in VA and VC. It contains high levels of manganese and phosphorus, but about 86% of the phosphorus contained is phytic phosphorus, which has poor utilization. Rice bran contains antitrypsin, which can be removed by heating, otherwise it can affect protein digestion when used in large quantities.
Wheat flour can produce 23-25% bran, 3-5% second flour and 0.7-1% germ flour. The quality of wheat bran varies with the processing precision. Bran is rich in beta vitamins but lacks B12. The water content of bran is better when it is below 12%. Bran contains fiber (8.5-12%), so the energy value is low, with metabolizable energy of only 7.1 MJ/kg. The crude protein content of bran is high, reaching 12-17%.
Roots, tubers and melons
The nutritional characteristics of this type of feed are high water content, generally 70-90%. As energy feed, it is mainly used for roots, stems and melons after removing water.
● sweet potato
Sweet potato, also known as red potato. Of the dry matter (90%) of sweet potato powder, soluble carbohydrates account for 80%. Most of them are starch. The crude protein content is 2%~4%, and the metabolic energy level is 11.72 MJ/kg. Only a small amount can be used when mixing ingredients. However, it has significant advantages when combined with urea and high-protein supplements.
● Cassava
About 90% of the dry matter in cassava flour is soluble carbohydrates, and most of it is starch. The protein content of cassava flour is very low, only about 3.8%; the crude fiber content is also very low, only about 2.8%; and it contains almost no fat. In addition to sweet potatoes and cassava, there are also potatoes, beets, carrots, etc. Their dry matter is rich in sugar and starch, with high energy and low protein content, and they all have the general common characteristics of energy feed.
Oil energy feed
The main purpose of adding oil to compound feed is to increase the energy level. In addition, it can prevent dust, facilitate pelleting, and improve palatability. Oil has a high energy concentration and is easily used by animals. For example, the energy content of fat can be as high as 39.3 MJ/kg. Calculated per unit weight, the energy contained in oil is 3 times that of pure starch and 3 times that of grain. If the price of oil is less than 3 times that of corn, it can be considered for use in feed.
Category 3: Protein feed
Protein feed refers to a type of feed with a crude fiber content of less than 18% and a crude protein content of greater than or equal to 20% in absolute dry matter. It includes four categories: plant protein feed, animal protein feed, single-cell protein feed and non-protein nitrogen feed.
Plant protein feed includes the following two categories:
(1) Legume seed feed: such as soybeans, broad beans, peas, etc. This type of feed contains both protein and energy before the oil is extracted (or squeezed out). After the oil is taken out, it becomes a feed with a higher protein content.
(2) Cake and meal feed: refers to the byproducts left after various seed feeds containing more than 20% protein are extracted for oil, such as soybean meal, cottonseed meal, rapeseed meal, and sesame meal. In addition, there are peanut cake and meal, sesame cake and meal, soy sauce dregs, vinegar dregs, tofu dregs, and rice protein powder.
Animal protein feed includes the following categories:
(1) Domestic fish meal, (2) Imported fish meal, (3) Blood meal, (4) Meat meal, (5) Meat and bone meal, (6) Other animal protein feeds (such as feather meal, silkworm pupa meal, earthworm meal, etc.).
Single-cell protein feed
Single-cell protein feed refers to a microbial protein feed that can be used as animal feed by using agricultural and industrial waste resources as the main raw materials to cultivate microorganisms for growth and reproduction. The microbial strains currently used to produce single-cell protein are mainly divided into four categories: yeast, bacteria, algae and fungi. Among them, yeasts include brewer’s yeast, tropical Candida, utilis, brewer’s yeast and Candida lipolytica, etc., and the yeast body contains 33%~45% protein; bacteria mainly include lactic acid bacteria, fecal streptococci, bifidobacteria, Bacillus, etc., and the protein content of bacterial cells is as high as 65%~85%; the most studied algae are Spirulina and Chlorella, and their cells contain 50%~60% protein; fungi are also widely used due to their rapid growth, mainly including molds such as Rhizopus, Aspergillus, Trichoderma and Penicillium, as well as edible fungi such as shiitake mushrooms and fungus, and their cell protein content is 50%~60%.
Non-protein nitrogen feed
Non-protein nitrogen feed in ruminant nutrition generally refers to simple nitrogen-containing compounds, such as urea, biuret, ammonium salts, etc., which can replace protein feed of plant or animal origin and feed ruminants to provide the nitrogen source required for synthesizing bacterial protein, thus saving animal and plant protein feed.
Category 4: Mineral feed:
Mineral feed is also an essential nutrient for animals. It participates in the metabolism of the three major nutrients (carbohydrates, proteins, and fats), forms the tissues and organs of animals, and regulates various physiological activities of animals. Mineral feed is divided into two categories, one is macro-mineral elements and the other is trace mineral elements, referred to as “trace elements”. Mineral feed sources are usually supplemented in the form of premixes.
Macro mineral elements: the content of this macro element in the body is not less than 0.01%, including phosphorus, sodium, magnesium, sulfur and chlorine;
Trace mineral elements: the content of trace elements in the body is less than 0.01%, including iron, steel, zinc, manganese, iodine, cobalt, selenium, cadmium, chromium, molybdenum, nickel, tin, etc.
Fifth category: vitamin feed:
There are 14 types of vitamins that have been identified, which can be divided into two categories according to their solubility: one is fat-soluble vitamins and the other is water-soluble vitamins:
Fat-soluble vitamins; including vitamin A, vitamin D, vitamin E, vitamin K;
Water-soluble vitamins: including vitamin B, vitamin B, vitamin B, vitamin B, vitamin C, niacin (nicotinic acid), pantothenic acid, folic acid, choline and vitamin H (biotin).
It is mainly supplemented in the form of premixes, and there are also some separate vitamin function packages.
Category 6: Air and water (the cheapest and most important)
These raw materials need to be processed reasonably, scientifically matched, and fed scientifically to meet the needs of healthy growth of animals. Violating the rules will cause various nutritional diseases.
