The need for nutrients in pigs

   mineral elements generally account for only 3%-4% in pigs, and are the main components of bones, some of which are distributed in hair, muscle, blood and other soft tissues, and some are components of vitamins, hormones and enzymes. Although these elements are not the source of energy, they can participate in metabolism, regulate osmotic pressure and maintain acid-base balance. They are necessary to maintain the normal physiological function and production of pigs, and they are scaffolds to support the physical state. There are many kinds of mineral elements, which can be divided into two categories: constant and trace according to the content in the body. Major elements account for more than 0.01% of body weight, such as calcium, phosphorus, sodium, chlorine, sulfur, magnesium, potassium and other elements; trace elements account for less than 0.01% of body weight, such as iron, copper, manganese, zinc, iodine, selenium and so on.

   (1) constant elements

   1, calcium and phosphorus are the most needed elements in pigs and make up the main components of bones.

   calcium plays an important role in maintaining the physiological function of nerve, muscle and heart, regulating acid-base balance, promoting blood coagulation and forming bones. The symptoms of rickets, osteomalacia, bone deficiency, slow growth, loss of appetite, pica, coma, cramps and jumping of suckling piglets were observed during calcium deficiency. Lactating sows due to the excretion of a large amount of calcium, calcium deficiency will lead to paralysis. On the other hand, boars show sperm hypoplasia.

   general pig diet calcium content accounts for 0.8%-0.9%, piglets and lactating sows should account for 0.9%, other pigs account for 0. 5%. 8%. The relationship between calcium and energy is that when energy increases, calcium should also increase. However, if the amount of calcium is too high, it will affect the absorption of magnesium, manganese and zinc in pigs, and it is also disadvantageous to their growth and production. Generally, there is little calcium in cereal feed and bran, so calcium feed such as stone powder, bone powder and calcium hydrogen phosphate should be added to the diet of pigs.

As the constituent element of bone,    phosphorus is second only to calcium in content. Phosphorus plays an important role in carbohydrate and fat metabolism, calcium absorption and utilization, and maintaining acid-base balance. Phosphorus deficiency has the same symptoms as calcium deficiency. The phosphorus requirement of pigs is 0.6%-0.7%. Grains and bran contain more phosphorus, but mainly in the form of phosphotrexate, but the utilization rate of phytic acid phosphorus in pigs is very low, so when combined with diet, available phosphorus should be used as the requirement index of phosphorus.

There is a close relationship between    calcium and phosphorus. Too high content of one element in feed will affect the absorption and utilization of another element. Therefore, the two must maintain a certain ratio, the ratio of calcium to phosphorus is generally required (1.5-1.2): 1.

   in addition, vitamin D also affects the absorption and utilization of calcium and phosphorus, the lack of vitamin D in the diet, calcium and phosphorus can not be well utilized, which will also cause calcium and phosphorus deficiency in pigs.

   2, sodium and chlorine are important components of blood and body fluids. They play a role in maintaining osmotic pressure, water and acid balance in pigs, and they are also closely related to cardiac muscle activity, protein metabolism, blood circulation, body temperature, increase appetite and hydrochloric acid for the formation of digestive juice. pigs lack both, and pigs have loss of appetite, retardation and idiophobia. It can be seen that whether salt is added to the feed is very important. However, salt should not be excessive, otherwise it will cause poisoning or diarrhea, and the most suitable amount is 0.5% to 1.0%.

   (2) Trace elements needed by pigs are iron, copper, zinc, manganese, diamond and iodine. Their functions to pigs are as follows:

   1, iron and copper: iron is an important component of heme, hemoflavin, myoglobin and cytochrome enzyme in pigs. Anemia is caused by iron deficiency, especially piglets are prone to anaemia, so newborn piglets should be injected with hemolysin or hemogenin. Copper and iron are closely coordinated. Copper participates in the digestion and metabolism of iron and accelerates the formation of heme, so copper deficiency also causes anaemia. Recent studies have found that copper also promotes growth, enhances immune function and antimicrobials. The daily iron requirement is 22 milligrams 250 milligrams according to the body weight during the growth stage, and the copper requirement is 1.3 milligrams and 9.33 milligrams, which can be even higher in high copper diet.

   2 and zinc are the components of many metabolic enzymes, especially for the composition of carbonic anhydrase in porcine cortex. The enzyme plays an important role in skin metabolism and hair gloss. Zinc-deficient pigs are prone to keratinization, cracking and depilation, slow growth, easy to suffer from dermatitis and so on. The daily requirement is 22,155mg. Zinc is deficient in general feed, so attention should be paid to the addition of zinc in compound feed.

  : found in liver, bone, spleen, pancreas and pituitary of pigs. It has an effect on the formation, growth and development of bones and is a component of some enzymes in carbohydrate, fat and protein metabolism. Manganese deficiency causes swelling of joints such as tibia and phalanges, which can seriously cause reproductive dysfunction in pigs, or form mummified fetuses and stillbirths. The daily requirement is 1mg to 22mg.

   4, cobalt: is the component of vitamin B12. Vitamin Bl2 is a vitamin that prevents anemia and promotes blood production, so cobalt deficiency also causes anaemia. 5. Selenium: it is a component of glutathione peroxidase. Selenium deficiency causes myocardial degeneration, liver necrosis, ventricular trifoliate water, decreased reproductive function and leukomyopathy. Piglets are more sensitive to selenium, and selenium deficiency dies quickly. There is a lack of selenium in the general feed in Henan Province, so selenium must be added when matching pig diets. Pigs need 0.03 to 0.08 milligrams per day.

   iodine: is the main component of thyroxine, iodine deficiency causes goiter, metabolic disorders and decreased fecundity in pigs. The daily requirement is 0.03-0.4 mg.