Detailed Explanation of the Nature and Application of Feeding Standards

  (1) The scientific nature, practicality and relative reasonableness of feeding standards

  Animal feeding standards are based on the theories of nutritional science and grounded in the results of production practice. All their indicators and values are derived from a large number of scientific experiments and have been verified through extensive intermediate testing and production practice, with reference to and reliance on a large body of domestic and international scientific literature. They reflect both the scientific aspect of nutritional requirements and the practical aspect, integrating theory with practice, and possess a high degree of scientific validity and practicality. For example, in recent years China has adopted its own formulated pig feeding standards, which have undergone intermediate testing and small-batch production verification. Using feeding standard 11667 pigs compared with 10101 pigs that did not use itpigs, the average feeding period was shortened by 25 days (125:150), the average daily gain per pig increased by 19.9% (560:467 grams), the lean meat rate increased by 21.7% (56%:46%), the feed conversion efficiency improved by 22.7% (0.27:0.22), and the average net income per finished commercial pig increased by 5.44 yuan. It can thus be seen that feeding standards possess high scientific validity and practicality and have a great guiding role in production practice. However, because actual production conditions are complex and diverse, the correct application of feeding standards and the nutritional requirements of animals are also subject to the influence of many factors, such as animal species, breed type, age, sex, physiological state, production level, production purpose, region, climate, feed conditions, feeding methods, environmental conditions and socioeconomic factors. Therefore, the scientific nature of feeding standards is relative to the blindness in production; they themselves have certain limitations. The requirement values they specify cannot be too detailed or too specific, and they reflect the average of a population, thus possessing a generalised character.

  (2) The universality, regionality and particularity of feeding standards

  Animal nutritional requirements and nutritional standards are reflections of observable phenomena and laws under certain historical conditions, and are reflections of the level of scientific and technological development at that time (period) and in that place (country). Due to the stability of germplasm characteristics within the same animal species, as well as the accumulation of scientific and technological knowledge and the improvement of production conditions, which are gradual and continuous over a certain period, the basic principles and many indicators among feeding standards from different periods share much in common, with a certain degree of inheritance between successive editions and relative stability. Since all countries in the world formulate feeding standards based on the common theoretical foundations and experimental methods of nutrition and feeding science, the basic principles and basic contents of feeding standards share much in common. One country's feeding standards are often adopted by other countries, or used as reference for formulating their own national feeding standards. Therefore, feeding standards also possess universality.

  It should be noted that in applying feeding standards to diet formulation, appropriate adjustments should be made according to actual conditions. Here, only vitamins are taken as an example. Vitamins are essential trace substances for livestock and poultry, but due to neglect or even one-sided understanding of vitamin nutrition in feeding, cases are repeatedly seen where vitamin deficiency leads to decreased productivity or even death of livestock and poultry. At present, whether domestic or international, vitamin nutrition standards are mostly expressed in the form of requirements, and some are expressed in the form of allowances that include a safety margin. Therefore, when trialling vitamin feeding standards, attention should be paid to understanding and distinguishing the difference between requirement and allowance. Requirement generally refers to the minimum amount that can maintain livestock and poultry health and allow production performance to be exerted under normal conditions, while allowance, in addition to considering the above factors, also needs to consider the total requirement including the ability of livestock and poultry to utilise vitamins under different physiological states and certain factors affecting vitamin utilisation. Practice has proven that the vitamin allowance is approximately 1 times its requirement. Thus, without a correct understanding of vitamin feeding standards, such as measuring long-term according to the requirement form, vitamin deficiency is bound to result. In particular, the exertion of high production performance by livestock and poultry over a relatively short period and certain external factors affecting vitamin utilisation will make vitamin deficiency symptoms in the body more obvious, and the resulting losses will be greater. How to properly manage the vitamin allowance for livestock and poultry on the basis of requirement is also constrained by many factors, and a certain degree of flexibility is needed in practical application. Generally speaking, there are the following aspects:

  1. The influence of production performance: the higher the production performance, the greater the requirement.

  2. The influence of diet nature: when feeding high-energy and high-protein diets, the demand for vitamins increases.

  3. The influence of environmental conditions: for example, under high-temperature conditions or restricted feeding, the reduced feed intake correspondingly causes an increase in vitamin demand. In addition, intensive feeding, cage rearing and the like reduce contact between livestock and poultry and manure and soil, all of which correspondingly cause an increase in vitamin demand

  4. The influence of disease or stress states: because they affect normal nutrient absorption function or increase consumption, the vitamin requirement increases.

  5. The influence of constraints between nutrients: for example, certain antagonistic relationships may arise between vitamins, and vitamins and certain trace elements may also produce constraining effects, all of which affect the actual allowance.

  6. The influence of vitamin efficacy: vitamin additives generally gradually decrease in efficacy over time. If green fodder is used to supplement vitamins, there is also the influence of processing methods. Furthermore, water-soluble vitamins are easily excreted in urine and are not stored in the body, while fat-soluble vitamins are not excreted in urine and can be stored in the body. Certain vitamins undergo excessive self-oxidation, and so on. Therefore, when practically applying vitamin feeding standards, full consideration should be given to various influencing factors, and feeding standards should be flexibly used to determine the vitamin allowance, so that livestock production can obtain better benefits.