Protein Nutrition of Chicken and rational Application of protein Feed

Protein is one of the most important nutrients in poultry, is the material basis of life, it is an important component of the body, participates in most of the biochemical reactions related to animal life, and plays an important role in animal life activities. The constituent unit of protein is amino acid, and feed protein is composed of 22 kinds of amino acids. amino acids form different forms of protein molecules through different arrangements and combinations. According to the speed of synthesis or synthesis in chicken, amino acids can be divided into two categories: one is essential amino acids, the other is non-essential amino acids. There are 13 kinds of essential amino acids in chickens, including methionine, lysine, threonine, tryptophan and isoleucine in general feed, which often affect the utilization of other amino acids when they are deficient, so these amino acids are also called restricted amino acids.

Protein feed refers to the feed in which the crude protein content in dry matter reaches or exceeds 20% and the crude fiber content is less than 18%. It is divided into plant protein feed and animal protein feed. Plant protein feed mainly consists of various oilseed meal (mainly soybean, cottonseed, peanut, rapeseed, etc.); animal protein feed includes fish meal, meat meal, meat and bone meal, blood meal, leather powder, feather meal, silkworm pupa meal (powder) and so on. The quality of protein is measured by the quantity and proportion of amino acids, and the content and quality of crude protein in various feeds vary greatly. In terms of its content, animal feed was the highest (40%-80%), followed by cruller (30%-40%), bran and Gramineae seeds were lower (7%-13%). As far as its quality is concerned, the protein quality of animal feed, legume and cruller feed is better.

When compounding feed, the application of protein feed should pay attention to the following problems:

1. The problem of amino acid balance: the type, quantity and proportion of essential amino acids in dietary protein are consistent with the needs of animals, that is, amino acid balance. The protein with amino acid balance is called "ideal protein". If the diet is prepared according to "ideal protein", the utilization rate of dietary protein is higher, the cost of feed is relatively lower, and the benefit is higher.

2. Prepare diets according to digestible amino acids: most dietary amino acids cannot be completely digested, and about 90% of the restricted amino acids in many commonly used raw materials such as corn and soybean meal can be digested, and there will be differences between individual amino acids. The amino acid digestibility of some plant protein feeds is very low, while the amino acid digestibility of animal protein materials varies greatly with the degree of heating. At present, the data of digestible amino acids in feed are not very complete, and the determination of digestible amino acids is slightly different due to the influence of cecal activity, endogenous nitrogen loss, urinary nitrogen loss and other factors. however, the preparation of diets according to digestible amino acids is the trend of ingredients in the future, which can not only make rational use of raw materials, but also improve poultry production performance, but also reduce the pollution of excreted nitrogen to the environment.

3. The synergistic effect of protein raw materials: the effect of using more than 2 kinds of protein feed is better than that of using single protein feed. For example, proper addition of peanut meal and cottonseed meal to corn-soybean meal diet makes amino acids easier to balance, reduces the amount of restricted amino acids, such as methionine, lysine and threonine, and reduces feed costs.

4. Some raw materials should be limited: there are antitrypsin, urease, hemagglutinin, saponin, goiter inducing factor, anticoagulation factor and so on. However, most of these harmful substances are not heat-resistant and can be decomposed by heating under suitable moisture, and the harmful effects can be eliminated. These nutritional inhibitory factors are less in soybean meal, and the dosage can be up to 35%. Cottonseed meal contains gossypol, cyclopropylene fatty acid, phytic acid, tannin and other nutritional inhibitory factors, and the amount of undetoxified cottonseed meal is generally less than 5%. Rapeseed meal contains glucosinolates, sinapine, phytic acid, tannin and other nutritional inhibitory factors, general dosage, chicks: 4% 5%; breeding chickens: 7% 8%; laying hens: 5% 8%, broilers later: 5%. The use of spoiled animal protein feed, such as fish meal and blood meal contaminated with salmonella, is prohibited.