What are the nutrient requirements of pigs?

  1. Energy

  The growth, development, reproduction, maintenance of body temperature and all activities of pigs require energy, and energy accounts for the largest proportion of nutrients. The energy needed by pigs comes from three organic substances in feed: carbohydrates, fats and proteins, and carbohydrates are the most important.

  Besides being supplied directly by glucose and volatile fatty acids absorbed by the digestive tract, the energy needed by pigs can also be supplied by glycogen and body fat in the liver, and when necessary, body protein can also provide energy after decomposition.

  The unit of energy is expressed in joules. In actual production, kilojoules or megajoules are commonly used. In the past, calories were used to express the unit of energy. The conversion between calories and joules is as follows:

  1 calorie = 4.184 joules

  1 kilocalorie = 4.184 kilojoules

  1 megacalorie = 4.184 megajoules

  After the organic substances in feed are completely oxidized in the pig's body, carbon dioxide and water are produced, and energy is produced at the same time. Pigs have the ability to maintain a constant body temperature. When the outside temperature drops, the body's metabolism strengthens and heat production increases in order to maintain body temperature, so more maintenance energy is consumed. Therefore, the energy level in the winter diet should be appropriately increased.

  Pigs have the ability to regulate feed intake. When the energy level of the diet is low, they will eat more, causing excess protein and waste; if the diet energy is too high, the pigs will become too fat, which will also cause waste of feed, and the pork quality will be low and the selling price will be low, bringing unnecessary economic losses. Because changes in feed intake affect the intake of protein and other nutrients, causing nutritional imbalance. Therefore, when formulating diets, the energy standard must first be determined, and then on this basis the requirements for other nutrients must be determined. The feeding standards for pigs in China use the ratio of protein to energy to specify the proportional relationship between protein and energy.

  2. Protein and amino acids

  Protein is the foundation of life. Without protein there is no life. The bristles, skin, nerves, blood, muscles, hoof shells, etc. of pigs all contain protein. Enzymes, hormones, antibodies and pigments in the pig's body are also synthesized from protein and other substances.

  Protein includes true protein and amides, collectively called crude protein. When formulating diets for pigs, the percentage of crude protein is often used as an indicator.

  Protein is composed of the common 20 amino acids in different proportions. The proteins in various feeds are decomposed by various digestive enzymes in the pig's digestive tract into peptones and peptides, and finally into various amino acids that can be absorbed by the intestinal tract. Essential amino acids refer to those amino acids that cannot be synthesized in the pig's body or cannot be transformed from other amino acids, or that can be synthesized but whose synthesis speed and quantity cannot meet their nutritional needs and must be supplied by feed. It is known that pigs have 10 essential amino acids including lysine, methionine, tryptophan, arginine, etc., and the first three are most needed and are called limiting amino acids because their content in feed is relatively low and it is not easy to meet the needs of pigs. The other 7 are non-limiting amino acids. Non-essential amino acids can be synthesized in the pig's body and do not necessarily need to be supplied by feed.

  The pig's nutritional requirement for protein is essentially a nutritional requirement for amino acids. The relationship between protein and amino acids is like a wooden barrel and each wooden stave that makes up the barrel. The lack or deficiency of a certain amino acid means that various proteins in the pig's body cannot be formed. The lack of a certain protein, that is, the lack of amino acids, leads to slow growth, rough bristles, late sexual maturity and poor development of piglets. However, an excess of certain amino acids not only reduces the utilization rate of protein, but also causes waste, and increases the burden on the liver during deamination.

  The amino acid content of feed proteins is not the same. Mixing several feeds in proportion allows the essential amino acids to complement each other, thereby improving the utilization rate of amino acids.