Effects of various mineral elements on dairy cows

According to the proportion of minerals in the animal body, they are divided into macro elements and trace elements. Macro elements refer to elements that account for more than 0.01% of the animal body; otherwise, they are trace elements. It has been confirmed that more than 20 kinds of mineral elements are necessary for dairy cows . Among the macro elements are calcium, phosphorus, sodium, chlorine, magnesium, potassium, sulfur, etc.; among the trace elements are copper, iron, zinc, manganese, cobalt, iodine, selenium, etc.

The main functions of minerals are: ① used as a growth and repair substance for body tissues; ② used as a regulator for animal bodies; ③ used in dairy production (the dry matter of cow milk contains 5.8% minerals). Some important mineral elements are explained separately below.

1. calcium

Calcium is the mineral element that dairy cows need the most, especially for dairy cows. Calcium mainly exists in bones and teeth, and only accounts for about 2% in tissues and body fluids. The functions of calcium include muscle excitation, heart regulation, nerve conduction, blood coagulation, milk production, etc. Calcium is absorbed mainly in the duodenum. There are three outlets for the excretion of calcium, namely feces, urine and sweat, among which the excretion in feces is the largest. If the supply of calcium in the feed is insufficient, and the body needs it very much, it will use the calcium in the bones. Such as early lactation, peak milk production and so on. If calcium is seriously deficient, it will lead to a sharp drop in milk production. However, the calcium content in milk is maintained at a high level. If calcium deficiency occurs in growing animals, rickets and rickets often occur.

Calcium requirements are affected by the individual conditions and production conditions of dairy cows. According to measurements, dairy cows need 8g of calcium per 100kR body weight per day, and 1.23g of effective calcium per 1.0kg of milk produced. It needs about 30g per day in the early stage of lactation, and about 10g in the late stage of lactation.

2. phosphorus

In addition to participating in the composition of the skeleton of the organism, phosphorus plays an important role in many biochemical and physiological aspects and is an essential substance for the metabolism of substances in the body. The absorption of phosphorus is mainly absorbed in the duodenal epithelium, and its absorption rate is affected by the source of phosphorus, the environment in the intestine, age and other factors. Its excretion mainly depends on the kidneys. If phosphorus is insufficient, it can affect growth rate and feed utilization, loss of appetite, lack of heat, and reduced milk production. Since calcium and phosphorus participate in bone formation at the same time, when phosphorus is insufficient, it will also cause chondrosis and rickets in the body. Pay attention to the ratio when supplementing calcium and phosphorus. Generally, the ratio of calcium and phosphorus should be within the range of 2:1-1:1.

The phosphorus requirement of dairy cows varies greatly due to body weight, age, and milk production. According to reports, dairy animals need 5.0g of phosphorus per 100kg of body weight per day, 8.0g in the late lactation period, and 13g in the late pregnancy period. Dairy cows with a daily milk production of 30kg need about 100g of phosphorus per day.

Phosphorus content in feed varies from source to source. Excessive phosphorus can cause abnormal bone development, and what's more, it can cause urinary stones and other diseases.

3. Potassium

Potassium is the third most abundant mineral element in the body and is essential for life. Potassium ions mainly exist in the intracellular fluid, and together with sodium, chloride and bicarbonate ions maintain intracellular osmotic pressure and maintain cell volume. Potassium is also involved in maintaining acid-base balance. It is also an indispensable factor in maintaining excitability of nerves and muscles. When the body is deficient in potassium, it manifests as growth retardation, muscle weakness, pica, allergies, etc.

It has been determined that when the proportion of forage grass in the diet is large, it is easy to meet the potassium requirement of dairy animals. Except for corn, the potassium content per kilogram of dry matter of various feeds is more than 5g, and the content of potassium per kilogram of dry matter in green feed exceeds 15g. Therefore, common feeds can meet the needs of animals for potassium.

4. sodium and chlorine

Sodium and chlorine work together to maintain the acid-base balance and osmotic pressure of body fluids. Sodium and chlorine are mainly distributed in the extracellular fluid, are the main ions to maintain the osmotic pressure and acid-base balance of the extracellular fluid, and participate in the metabolism of water. Sodium and other ions participate in maintaining the excitability of normal muscle nerves and regulate myocardial activity. Sodium can inhibit excessive acid production in the rumen of ruminants and create a suitable environment for the activities of rumen microorganisms. Chlorine is the main anion in gastric juice. It combines with hydrogen ions to form hydrochloric acid, activates pepsin, and makes gastric juice acidic, which has a bactericidal effect. The excretion of chlorine and sodium is mainly excreted through urine, and less excreted through feces and juice. When the animals are deficient, there are no obvious symptoms, only the growth performance of the animals is hindered, the feed conversion rate is reduced, and the production performance of adult animals is reduced.

Ruminants need sodium supplementation because plants generally contain less sodium. According to research, in the diet, it is often advisable to ration salt at 0.05% of body weight. About 8 mg of sodium is needed per 100 kg of body weight. In the hot season or during the growth and lactation periods, the body's demand for salt increases. The salt in the general dairy cow ration accounts for 0.5% of the dry matter of the dairy cow ration.

5. magnesium

About 70% of the magnesium in the animal body exists in the bones and teeth in the form of salt. Magnesium is related to the activity of certain enzymes, is an activator of many enzymes in the body, and plays an important role in sugar and protein metabolism. A certain concentration of magnesium can ensure the normal function of nerves, muscles, and organs. When the concentration of magnesium is low, the excitability of nerves and muscles is increased, and when the concentration is high, it is inhibited. The early stage of magnesium deficiency in ruminants is manifested by peripheral vasodilation and increased pulse rate. Subsequently, the magnesium content in the blood decreases, and when it falls to a certain level, the body will appear nervousness, tremors, muscle spasms, etc. Magnesium deficiency is often regional. According to the US NRC (1980), the maximum tolerated amount of magnesium is 0.4% of the diet, and the magnesium in the diet is usually far below the toxic level.

6. sulfur

Sulfur in animals is distributed in every cell of the body. In addition, it also exists in vitamins and thiamine, and a small amount is in an inorganic state. Sulfide plays an important biochemical role in metabolism. Dietary sulfur deficiency can cause loss of appetite, weight gain, hair growth, and milk production. The lack of sulfur is related to the type of feed, so rumen microorganisms can use inorganic sulfur and non-protein nitrogen to synthesize sulfur-containing amino acids. If non-protein nitrogen (such as urea) is rationed in the diet, sulfur must be supplemented. It is advisable that the amount of supplement should not exceed 1.5g per kilogram of dry matter feed.

7. iodine

The content of iodine in the body is very small, and it is mostly concentrated in the thyroid gland, but its function is very important. It is closely related to metabolism, participates in the metabolic process of many substances, and has an important impact on animal health and production. When iodine is deficient, the metabolism of animals is reduced, goiter is enlarged, and development is hindered. In order to prevent the lack of iodine, 1% iodide containing 0.015% can be added to the feed or a little inorganic iodine can be mixed into the water to drink and feed to achieve the desired effect. The supplementary amount of iodine should not be less than 0.6me per kilogram of dry matter feed.

8. selenium

Selenium is distributed in all tissues of the body, especially in the moon stem, kidney and muscle. Selenium is the main component of glutathione peroxidase, which depends on selenium to activate. Selenium and vitamin E have similar antioxidant effects, which can decompose peroxides produced by tissue lipid oxidation and protect cell membranes from damage by lipid metabolism by-products. Insufficient selenium can cause white muscle disease, liver necrosis, growth retardation, and decreased fertility. The main cause of selenium deficiency is caused by the lack of selenium in the soil. In selenium-deficient areas, the supplementary amount should not exceed 0.3 mg per 1.0 kg of dry matter feed.

9. iron

About 70% of iron in animals exists in blood and muscle, and some iron combines with protein to form ferritin, which is stored in liver, spleen and bone marrow. The main function of iron is to serve as an oxygen carrier to ensure the normal delivery of oxygen in body tissues, and to participate in the biological oxidation process in cells. Iron deficiency often presents as anemia, especially in young livestock. It is reported that the iron requirement of ruminant livestock is 50mg/kg in every kilogram of feed dry matter.

10. zinc

Zinc is a component of various enzymes in livestock, and it is also a component of insulin, which participates in the metabolism of carbohydrates. When zinc is deficient, the growth of animals is hindered, and the coat is easy to fall off. Dairy cows contain about 20mg/kg of zinc. For high-yield cows, the zinc content per kilogram of feed dry matter must reach 40mg/kg to prevent zinc deficiency.

11. copper

Copper is one of the building blocks of hemoglobin, an activator of many enzymes in the body. The production of red blood cells, the formation of bones, and the deposition of hair pigment all require the presence of copper. If there is a lack of copper, pathological phenomena such as anemia, movement disorders, and abnormal bone metabolism will appear. Generally, the requirement of copper for dairy cows is 8-10mg/kg.

12. cobalt

Cobalt is one of the essential trace elements for ruminants. Its main function is as a component of vitamin B12. Ruminant microorganisms in the rumen can use cobalt to synthesize vitamin B12 and absorb it. Therefore, when there is a lack of cobalt, there will be a deficiency of vitamin B12. Manifested as malnutrition, growth stagnation, emaciation, anemia and so on. It is advisable that the daily cobalt supplementation of dairy cows is 0.1mg/kg. The maximum tolerated amount of cobalt is 10mg/kg.

The above is just a brief description of the role of some important trace elements on dairy cows. Although many mineral elements are closely related to the health of livestock, they are not easily lacking in general diets, so I will not elaborate on them one by one.