The need for nutrients in pigs

   1. Energy

The growth and development, reproduction, maintenance of body temperature and all activities of    pigs need energy, which accounts for the largest proportion of feed materials. The energy needed by pigs comes from three kinds of organic matter in feed: carbohydrates, fat, protein, and carbohydrates are the most important.

In addition to glucose and volatile fatty acids absorbed directly from the digestive tract, the energy required by    pigs can also be supplied by glycogen and body fat in the liver, and body protein can also provide energy after decomposition if necessary.

The unit of    energy is expressed in joules. Kilojoules or megajoules are commonly used in production practice. In the past, cards were used to represent energy units, and the conversion between cards and joules is as follows:

   1 card = 4.184 joules

   1 kcal = 4.184 kJ

   1 mega card = 4.184 megajoules

After complete oxidation of organic matter in    feed in pigs, carbon dioxide and water are formed, and energy is produced at the same time. Pigs have the ability to maintain constant body temperature. When the external temperature decreases, the metabolism of the body is enhanced and heat production is increased to maintain body temperature, which consumes more energy. Therefore, the energy level in winter diet should be increased appropriately.

   pigs have the ability to adjust feed intake, when the dietary energy level is low, they will eat more, resulting in excess and waste of protein; too high dietary energy will make pigs too fat, and will also cause feed waste, and low pork quality, low selling price, resulting in undue economic losses. Due to the change of food intake, it affects the intake of protein and other nutrients, resulting in nutritional imbalance. Therefore, when matching the diet, we must first determine the energy standard, and then determine the feeding standard of pigs for other nutrients on this basis, and use the ratio of protein to energy to determine the ratio of protein to energy.

   II. Protein and aminoacid

   protein is the foundation of life. Without protein, there is no life. Pig coat, skin, nerve, blood, muscle, hoof shell, etc., contain protein. Enzymes, stimuli, antibodies and pigments in pigs are also synthesized by proteins and other substances.

   proteins include pure proteins and amines, which are collectively called crude proteins. When feeding pigs with diets, the percentage of crude protein is often used as an index.

   proteins are composed of different proportions of 20 common amino acids. The proteins in various feeds are decomposed into peptone, peptides and peptides by various digestive enzymes in the digestive tract of pigs, and finally into various amino acids that can be absorbed by the intestines. Essential amino acids mean that pigs cannot be synthesized from other amino acids, or can be synthesized, but the speed and quantity of synthesis can not meet their nutritional needs. however, the essential amino acids that must be supplied by feed are lysine, methionine, tryptophan, arginine, and so on, and the first three are most needed and are called restricted amino acids, because they are less in feed. It is not easy to meet the needs of pigs, and the other 7 kinds of amino acids are unrestricted amino acids. Non-essential amino acids can be synthesized in pigs and may not be supplied by feed.

The nutritional needs of protein in    pigs are essentially the nutritional needs of amino acids. The relationship between protein and aminoacid is like a wooden barrel and every board that makes up a barrel. The lack or deficiency of a certain amino acid can not constitute all kinds of proteins in pigs. The lack of a certain protein, that is, the lack of amino acids, leads to growth retardation, rough coat, late sexual maturity and poor development of piglets. However, the excess of some amino acids will not only reduce the utilization rate of protein, but also cause waste and increase the burden on the liver in the process of deamination.

The amino acid content in the protein of    feed is different. If several kinds of feed are mixed in proportion, the essential amino acids can complement each other, which will improve the utilization rate of amino acids.