Types and functions of common feed additives for dairy cows
In order to supplement nutrients, improve the performance of dairy cows, increase the utilization rate of feed, improve feed quality, and promote the growth and reproduction of dairy cows, small or trace feed additives can be added to the feed. The commonly used feed additives for dairy cows mainly include vitamin additives, macro element additives, trace element additives and rumen buffer regulators. Chinese herbal medicine is also a type of additives commonly used at present.
Vitamins are low-molecular compounds necessary to maintain the normal physiological functions of dairy cows. They play an important role in the growth and development, reproduction and lactation of dairy cows. They are essential nutrients for maintaining life. Lack of one or more vitamins in the feed will cause physiology disorders in dairy cows and vitamin deficiencies. For example, when vitamin A is lacking, the growth and development of the calf is restricted, and growth stagnation occurs, and the coat is rough and dull. The cow has a low conception rate and is prone to diseases such as metritis after delivery, which seriously affects the production of dairy cows. Performance: When vitamin D is deficient, calves suffer from rickets, and adult cows show osteoporosis; lack of vitamin E can cause dyskinesia in calves and decrease the reproduction rate of adult cows.
Vitamins can be divided into fat-soluble and water-soluble according to their solubility. Fat-soluble vitamins include vitamin A, vitamin D, vitamin E and vitamin K; water-soluble vitamins include vitamin B vitamins and vitamin C. In general, except for calves, dairy cows at other physiological stages do not need additional vitamin C, vitamin K and B vitamins. This is because the rumen microbes of dairy cows can synthesize B vitamins and vitamin K, and the liver and kidneys can synthesize them. Vitamin C. Generally, when the roughage for dairy cows is mainly crop straw, it will cause vitamin A deficiency and affect the reproductive performance of dairy cows, so additional vitamin A should be supplemented. In addition, in order to meet the vitamin requirements of dairy cows in different physiological periods, other vitamins, such as vitamin D and vitamin E, should be supplemented appropriately.
The amount of vitamins to be added depends on the type of cow and the demand for vitamins in different physiological periods. The addition of vitamins should not be excessive. Excessive amounts will not only cause waste, but also adversely affect the health and production performance of the cows. For example, an excessive amount of vitamin A can lead to decreased appetite, joint swelling and pain, bone hyperplasia, and weight loss; excessive vitamin D can cause increased blood calcium.
2. Constant element additives
Dairy cows consume a lot of minerals during lactation. The mineral elements in the diet cannot meet the lactation needs of dairy cows, so additional supplements must be made. Insufficiency of minerals in the diet will have adverse effects on the growth, reproduction and health of dairy cows. It will also affect the quality of milk and cause corresponding deficiencies in milk mineral elements. Insufficient calcium and phosphorus in the calf’s diet can lead to rickets in the calf. In the early stage of the disease, dairy cows show loss of appetite, listlessness, weight loss, unkempt coat, and movement disorders. As the course of the disease progresses, it gradually appears. Skeletal dysplasia, unossified tissue at the end of the bone becomes thick, and the spine and sternum are bent and deformed. Insufficient calcium and phosphorus in the diet of adult dairy cows can lead to chondrosis or osteoporosis, loss of appetite, affect their feed intake and production performance, reduce milk production, and affect the reproductive performance of the cow.
In actual aquaculture production, mineral supplementary feeds mainly include salt, dicalcium phosphate and stone powder. Table salt contains sodium ions and chloride ions. Among them, sodium ions play an important role in maintaining the acid-base balance in the body and maintaining the normal osmotic pressure of body fluids, while chloride ions maintain the osmotic pressure of the extracellular fluid and ensure the performance of pepsin. The required pH value plays an important role. In addition, salt can increase the appetite of cows and stimulate the secretion of saliva. Dairy cows are short of salt for a long time, and their milk production and productivity have decreased; calcium hydrogen phosphate and stone powder are commonly used to supplement calcium and phosphorus mineral feeds for dairy cows.
3. Trace element additives
Using trace elements to balance the diet can effectively increase the production level of dairy cows and the rate of estrus and conception of cows. Iron, copper, and cobalt are indispensable elements for hematopoiesis; manganese is a component of many metabolic enzymes and one of the essential components for the formation of chondroitin sulfate, which can promote the body's calcium and phosphorus metabolism and bone formation; used as a dairy cow's diet Long-term lack of trace elements will affect the growth and reproductive capacity of dairy cows. For example, the lack of iodine will reduce the metabolic function, hinder growth and development, and make dairy cows lose their fertility.
Buffers are mostly used in the primary dairy cows at the early stage of lactation or dairy cows whose diet contains more than 50% to 60% concentrate. Long-term feeding of silage to dairy cows will increase the acidity of the rumen. At this time, it is also necessary to add buffers; in summer, dairy cows often experience a decrease in appetite, which will lead to a decrease in feed intake. Affect lactation, in this case you can also add buffers to the diet. Buffers can increase the milk fat rate in the milk produced by cows. When the milk fat rate drops significantly, buffers can be used for adjustment.
There are many types of buffers, generally sodium bicarbonate (baking soda), and others include sodium carbonate and magnesium oxide. The addition of sodium bicarbonate accounts for about 1.4% to 3% of the concentrate; the addition of magnesium oxide accounts for 0.6% to 0.8% of the concentrate.
