The nutritional needs of dairy cows mainly include maintenance needs and production needs. Maintenance needs are the needs of maintaining the normal life activities of the cattle, while production needs mainly include the needs of growth, development, reproduction, milk production and weight gain. The nutrients needed to maintain the nutrition of dairy cows mainly include dry matter, energy, protein, minerals, vitamins, cellulose and water. 

 

1 、Dry matter intake

Dry matter is the general term for other substances in feed except water. The nutrients needed by cows are basically included in the dry matter, so food intake is an important indicator of dairy cow diets. He is vital to the health and production of cows. Predicting dry matter intake can effectively prevent over-feeding and under-feeding of cows and improve the utilization rate of nutrients. If the nutrient intake is insufficient, it will not only affect the production level of dairy cows, but also affect the health of dairy cows; on the contrary, if there are too many nutrients, excessive nutrients will be discharged into the environment. It will cause feed waste, increase feeding costs, affect health, and increase the incidence of metabolic diseases.

“Feeding standards for dairy cows”recommend dairy cows dry matter needs:

Reference dry matter intake for partial concentrate diets (Kg）=0.062W0.75 0.04Y

Reference dry matter intake for roughage diets (Kg）=0.062W0.75 0.45Y

Where:

Y --Standard milk weight, in kilograms (Kg）

W --Weight, in kilograms (Kg）

4%Standard milk for milk fat percentage (FCM) (Kg）= 0.4 ×Milk volume (Kg）15 xMilk fat (Kg）

In China's "nutritional needs and feeding standards for dairy cows", there are clear provisions for different weight physiological stages of dairy cows.

 

2、 Energy needs

The energy requirements of dairy cows can be divided into maintenance, growth, pregnancy and lactation. Both insufficient and excess energy can have adverse effects on cows. If the energy supply is insufficient, the growth and development of young cattle will be blocked, and the initial period will be prolonged. If the energy supply of dairy cows is lower than the milk production demand, not only the milk production will be reduced, but also the lactating cows will consume their own nutrition and convert it into energy to maintain life and reproduction needs, which will cause reproduction dysfunction in serious cases. Excessive energy can lead to obesity, cows will appear sexual cycle disorder, difficult pregnancy, dystocia and so on. It will also cause a large number of fat deposits in the breast, hinder the normal development of breast tissue, affect the function of lactation and lead to a decrease in lactation.

 

3、 The need for protein

Protein is the main component of various organs and tissues such as cells, blood, bones, muscles, hormones, milk fur, etc. It is of great significance to the growth, development, reproduction and production of dairy cows. When the supply of protein in the feed is insufficient, the digestive function of dairy cows decreases, showing slow growth, reproductive disorders, disease resistance, tissue organs and structural dysfunction, which seriously affects the health and production of dairy cows. The requirements for maintenance, milk production, pregnancy digestible crude protein and small intestine digestible crude protein of cows are listed in detail in the table of "Dairy Cow Nutrition Needs and Feeding Standards" in China. To calculate the required quantity, just look up the data in the table.

 

4 、The need for crude fiber

Crude fiber in feed is particularly important for the nutritional significance of ruminants. The analysis index of feed crude fiber is commonly used crude fiber (CF), acid detergent fiber (ADF) and neutral detergent fibers (NDF), and the best indicator of fiber is neutral detergent fiber. Dairy cows are herbivorous livestock, the diet must require a certain amount of plant fiber, the lack of fiber in the diet or forage is too short, will lead to indigestion, rumen pH decline, easy to cause acidosis, hoof leaf inflammation, true stomach displacement, and can make dairy cows milk fat rate decreased. If the proportion of plant crude fiber in the diet is too much, it will reduce the energy concentration of the diet, reduce the dry matter intake of milk, the same adverse to dairy cows.

The main reasons for this are:

First, crude fiber is not easy to be digested and has a large amount of water absorption, which can fill the intestines and stomach and give cattle a sense of satiety. Second, crude fiber can stimulate the rumen wall, promote ruminal peristalsis and rumination, and maintain the milk fat rate.

 Cow diets are required to contain at least15%～17%of crude fiber. General high-yield dairy cow diets require crude fiber to exceed17%Crude fiber in the diet of cows during the dry milk period and the end of pregnancy was20%～22%. Expressed in terms of neutral detergent fiber, dairy cow diet neutral detergent fiber in28%～35%between the most ideal. In actual production, the proportion of concentrate in the dry matter of the dairy cow's diet should not exceed60%In this way, a sufficient amount of crude fiber can be provided.

 

5 、Mineralsthe need

According to the size of the proportion of minerals in the animal body, the cow health material needs can be divided into constant elements and trace elements, the proportion of animal body in.0.01%The above are constant elements, includingCalcium, phosphorus, sodium, chloride, magnesium, potassium, sulfur, less0.01%For trace elements, including copper, iron, zinc, manganese, cobalt, iodine, fluorine, chromium and so on.

(1) calcium and phosphorusthe need

 Calcium is the most required mineral element for dairy cows, especially for lactating cows. inside the cow.98%Of the calcium is found in bones and teeth, and the rest is found in soft tissues and extracellular fluid. In addition to participating in the formation of bones and teeth, calcium is also involved in the excitation of muscles, the regulation of rhythmic contraction of the heart, the conduction of nerve excitation, blood coagulation and milk production. The lack of calcium leads to the decline of milk production and feed intake of dairy cows, and various skeletal symptoms appear, such as rickets of young animals, osteomalacia of adult animals, and lactosis of dairy cows (parturition paralysis).

 In addition to the composition of the body's bones, phosphorus is an indispensable substance for many physiological and biochemical reactions in the body. If phosphorus is insufficient, animals suffer from rickets, adult animals suffer from osteomalacia, growth rate and feed utilization rate decrease, loss of appetite, pica, decreased milk yield, lack of estrus, abnormal estrus or repeated infertility.

 Cows discharge a large amount of calcium and phosphorus from milk every day. It is common for cows to lack calcium and phosphorus due to insufficient calcium and phosphorus in the diet or low utilization rate of calcium and phosphorus. The ratio of calcium to phosphorus in the diet is usually1～2:1is appropriate. In China's "nutritional needs and feeding standards for dairy cows" (2004) The table details the maintenance of cows, milk production, and calcium and phosphorus needs of pregnant cows. That is, to maintain the need for each100kg weight6grams of calcium and4.5grams of phosphorus; per kilogram of standard milk4.5grams of calcium and3G phosphorus can meet the needs. Growing cattle need to be maintained per100kg weight6 grams of calcium and4.5grams of phosphorus; one kilogram for each additional weight20grams of calcium and13grams of phosphorus can meet the needs.

 

(2) The need for salt

Salt is mainly composed of sodium and chlorine. Sodium and chloride are mainly distributed in the extracellular fluid and are the main ions to maintain the external osmotic pressure, acid-base balance and metabolic activities. Cows lack of salt will produce pica, loss of appetite, decreased milk production and so on. Salt requirement as a percentage of the dry matter intake of dairy cows0.46%Or according to the batch1%It can be calculated. The amount of dry matter fed by non-producing cows0.25%～0.3%Calculations. The amount of salt needed to maintain a cow is about per100kg body weight3grams, per production1kg of standard milk supply1.2g.

 

6 、The need for vitamins

Vitamins are divided into two categories: fat-soluble and water-soluble. Fat-soluble including vitaminsA,D,EandKwater-soluble including vitaminsBClan and VitaminsC. Vitamin is an essential nutrient for dairy cows to maintain normal production performance and health, and has a variety of biological functions such as metabolic immunity and gene regulation. Vitamin deficiency can lead to a variety of specific deficiency diseases, seriously affecting the normal production performance of dairy cows. General for cattle only vitamin supplementsAVitaminsDVitaminsEThat is, vitaminKIt can be synthesized in the rumen, and water-soluble vitamins can be synthesized by rumen microorganisms. Studies have shown that in the modern dairy production system, only rely on rumen synthesis, some water-soluble vitamins may not be able to meet the needs of high-yielding cattle.

(1) VitaminsA

 VitaminsAIt is very important for dairy cows. It is related to the growth and development of visual epithelial tissue, reproductive bone, corticosterone synthesis and cerebrospinal fluid pressure. VitaminsADeficiency is characterized by corticization of epithelial tissue, loss of appetite, followed by multiple tears, keratitis, dry eye disease, and sometimes permanent blindness. Pregnant cow vitaminAAbortion can result in miscarriage, premature birth, and birth of stillborn malformed fetuses or blind calves.

Vitamins Needed for CowsAMainly from the diet.Beta-Carotene, vitamin contained in plant feedAof precursor substancesBeta-Carotene, which converts vitamins in animalsA, but in general, the conversion rate is very low, generally fresh young pasture containsBeta-More carotene than older ones,Beta-Carotene is easily oxidized and destroyed during the drying and storage of green forage grass, and its titer is obviously reduced. And the vitamins of the plant feedAThe content is affected by many factors such as the maturity of plant species and storage time, and the variation is very large. Therefore, in most cases, especially in high concentrate diets, high corn silage diets, low-quality coarse diets, poor feeding conditions and reduced immune function, additional vitamin supplements are requiredA.

The carotene content in the actual diet varies greatly, and there is no way to know the actual content of carotene in the diet in the actual production.

Additional vitamin supplementation should be considered especially under the following conditionsA:

a Low roughage diet: long-term low roughage diet of cattle, the rumen of vitaminAThe degree of destruction is higher, and the carotene is taken.dLess in.

b A diet based on a large amount of silage corn and a small amount of forage grass: this diet contains very little carotene.

cDiets fed with inferior roughage: the content of carotene in the diet was very small.

d Cows in the perinatal period: the immune activity of cows during this period is reduced, and the immune system is sensitive to vitamins.AIncreased demand

 

(2) VitaminsD

 VitaminsDis to produce calcium-regulating hormones1,25-dihydroxy vitaminDThis hormone can improve the activity of small intestinal epithelial cells transporting calcium and phosphorus, and enhance the activity of parathyroid hormone, improve bone calcium absorption, which is of great significance for maintaining the stability of calcium and phosphorus in the body and maintaining the normal of bones and teeth.1,25-dihydroxy vitaminDIt is also associated with the maintenance of immune system function, usually promoting humoral immunity and suppressing cellular immunity. VitaminsDThe basic function is to promote the intestinal absorption of calcium and phosphorus, maintain the normal concentration of calcium and phosphorus in the blood, and promote the calcification of bones and teeth. VitaminsDLack will reduce the ability of cows to maintain the balance of calcium and phosphorus in the body, resulting in the ability of calcium and phosphorus balance in plasma, resulting in a decrease in the concentration of calcium and phosphorus in plasma, causing rickets in young animals, osteomalacia in adult animals, and rickets in young animals. In adult animals, lameness and bone fractures are both vitaminsDCommon Consequences of Lack.

Since cows are sensitive to vitaminsDIt is difficult to define the need for vitamin supplements, and it is generally believed that cows who eat sun-dried hay and receive sufficient sunlight do not need vitamin supplements.DVitamins for green feed corn silage and artificial hayDThe content is also richer, but vitamin supplements are given to high-yielding and dry cows.DIt can improve the performance of milk production and reproduction.

(3) VitaminsE

VitaminsE The physiological function is mainly to act as an antioxidant for fat-soluble cells, protect the integrity of the membrane, especially the sub-cell membrane, enhance the immune response of cells and body fluids, and improve disease resistance and reproductive function. White myopathy is a typical vitaminEClinical deficiency disease, reproductive disorders, milk production fever and decreased immunity and other problems are also related to vitaminEThere are different degrees of relationship. When selenium is sufficient, add vitamins to cows during the dry milk period.EIt can reduce the incidence of placenta, breast infection and mastitis.

Due to the effects of vitaminsEThere are many factors needed. In practical production, vitamins can be adjusted according to the following conditionsEAddition:

(1) Reduce vitamins when feeding fresh pasture.EThe amount of addition. When fresh forage accounts for the dry matter of the diet50%When, vitaminEThe amount of addition is lower than that of the same amount of stored forage.67%;

(2) When fed low-quality forage diets, vitaminEThe amount of addition needs to be increased;

(3) When the selenium content in the diet is low, more vitamins need to be addedE;

(4) Due to colostrumΑ-Tocopherol content is higher, so in the colostrum period need to improve vitaminElevel of addition;

(5) immune suppression period (such as the pre-perinatal period), the need to improve vitaminElevel of addition;

(6) When there are more unsaturated fatty acids and nitrites in the feed, it is necessary to increase vitamins.Elevel of addition;

(7) Plenty of vitamin supplementsEIt helps to reduce the oxidation odor in milk.

（4）VitaminsK 

 VitaminsKHas anti-bleeding effect, under normal circumstances, the cow rumen microorganisms can synthesize a large number of vitaminsK

(5) Water-soluble vitamins

  Rumen microorganisms can synthesize most of the water-soluble vitamins (biotin, folic acid, niacin, pantothenic acid, vitaminB6riboflavin, vitaminB1VitaminsB12), and these vitamins are high in most feeds. Water-soluble vitamin requirements during lactation of calves can be met by milk. 

 

7、 The need for water

Water is the most important nutrient for cows. All processes of life require the participation of water, such as maintaining body fluids and normal ion balance, digestion, absorption and metabolism of nutrients, excretion of feces, urine and sweat, and body heat. 

Dairy cows need water from drinking water, feed water, and metabolic water in the body. Among them, drinking water is the most important, and the drinking water of dairy cows is affected by many factors, such as milk yield, dry matter intake, climate conditions, water quality and so on. Therefore, in order to ensure the drinking water of cows, we should do the following:

1 adequate drinking water, generally take free drinking water;

2 high quality water source, drinking water must be clean, pollution-free; conditional at the same time to test the quality of water, salt, soluble solids and soluble salt, hardness, nitrate,PHValue (6.5～8.5), contaminants, bacterial content, etc.

3 reasonable drinking water environment and conditions, such as water temperature, drinking water near the ground to be flat, spacious, comfortable and so on.