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Compared with large-volume feeds, concentrates in dairy diets have high nutritive value but are expensive. Concentrates generally account for more than 50% of the grain, saving on concentrate feeds saves food. At present, the developed countries of the dairy cows are all trying to reduce the proportion of concentrates in the dairy cow's diet in order to reduce the consumption of concentrates per unit of milk products. The high proportion of concentrate feed in the dairy cow diet will not only increase the cost of raising cows, but will also lead to material metabolism disorders and decrease of milk fat percentage. When the proportion of concentrates exceeds 50%, the acetic acid fermentation in the rumen of dairy cows is inhibited, the milk fat percentage is reduced by 0.2%--0.3%, the metabolism of protein and minerals is disordered, and the reproduction rate is decreased. Therefore, in order to make the cows nutritionally balanced and economically reasonable, we should maximize the use of high-quality and large-volume feeds on the premise of satisfying the body's needs for energy and biologically active substances. The concentrate feed is mainly used to balance the energy and protein levels of the dairy cow diet. The consumption of concentrate per kilogram of milk should not exceed 250-350g/year. The level of concentrates in dairy cows' diets increased with the increase in milk production. Tests have shown that the best ratio of dairy cows with annual output of milk 2500--3000kg is 14% - 18%, the annual output of dairy milk is 3500--4000kg is 21% - 25%, and milk production is 4500 - - 5000kg for 30% - 35%, annual milk production 5500 - 6000kg for 37% - 39%. The proportion of concentrate feed in the high-yielding dairy cow diet will inevitably increase because the large-volume feed affects the dry matter intake of the cow. If the proportion of large-volume feed in the dairy cow's diet is too high, its quality can no longer meet the energy needs of the high-yielding dairy cow. Dairy cows can feed a large volume of feed when they produce less than 10 kg of milk per day. When more than 10 kg of milk are produced, they should be fed with concentrated feed. Feeding 1kg of dry matter per cow can reduce 0.4kg of feed intake for large-scale feeds in the early stage of lactation, and reduce 0.42kg in the middle period of lactation and 0.6kg in the late period of lactation. Dairy cows with an annual output of 4,000 to 5,000 kg of milk account for 3,000 kg of milk produced with large-scale feed, and 2,600 kg of milk cows with an annual output of 6,000 kg of milk. Insufficient and poor quality of large-volume feeds (rough and juicy) will significantly increase the consumption of dairy concentrates. For example, when the hay quality is good, the dairy cow should produce 20kg of milk per day, and each batch of 1kg of milk needs to feed 250g of concentrated material, and when the quality of hay is poor, the same amount of milk production is obtained. The cow needs to consume 500g of concentrated material. Under the conditions of high-quality hay, silage, root feed, and pasture grass, when dairy cows produce 3000--4000kg of milk per year, only about 100--200g of fine material per 1kg of milk is consumed. Tests have shown that dairy cow diets containing high quality hay can reduce concentrate consumption by 40% and reduce milk costs by 14%. Therefore, reducing the proportion of concentrates in dairy cow diets should be based on the premise of ensuring the quantity and quality of large-volume feeds. In the production of dairy cows, the composition of concentrates should be adjusted according to the feeding characteristics at different times of the year to meet the nutritional needs of the planned milk production. During the summer grazing period, under the conditions of rational use of pasture and forage grass, when the crude protein content in the dry matter of grass is above 14%, it is sufficient for a dairy cow with a daily output of 20 kg. The concentrate synthesis at this time should reduce or eliminate the use of cake-type feeds with high protein content, use easily hydrolyzed carbohydrates (such as starch and sugar) and mineral elements to balance the dairy cow diet so that the cows can effectively use the protein in the green feed. . Dairy cows' summer concentrate feed should be used as a source of energy for milk production. Dairy cows with a daily output of 12--15 kg or more should be fed concentrate feed. The amount of concentrate should be determined according to the quality of pasture. In the case of high quality forage (digestible crude protein content of 12% - 14%, crude fiber content of 22% - 25%), only 1kg of milk is fed. Concentrate 100--150g; In the case of medium-quality herbage (digestible crude protein content of 10% - 12%, crude fiber content of 30% or more), 1kg of milk should be fed with 250-300g of concentrate . During the feeding period, when dairy cows are fed high-quality hay, silage corn, sugar residue and tuber feed, the content of the cake feed should be increased in the concentrate to supplement the deficiency of the protein in the diet. Dairy cows require different dietary energy concentrations at different stages of lactation, especially for high-yielding cows. In order to make rational use of concentrate feed, the appropriate amount of concentrate should be determined according to the lactation period of the cow. In the pre-lactation period (1 day - 100 days), the amount of concentrate feed should account for 44% - 45% of the total feed amount of the concentrate; in the mid-lactating period (101 days - 200 days), it should account for 36% - -37%; at the end of lactation (201 days - 305 days), should account for 18% - 20%. When dairy cows produce 3000--5000kg of milk per year, 1kg of milk will be fed into concentrate 200--400g per 1kg of milk during the pre-lactation period, 1kg of milk will be fed 160--360g of concentrated material during the mid-lactation period, and 1kg of milk will be fed to concentrate during the late lactation period. 130--250g. In short, the concentrated feed of dairy cows should be reasonably used according to the structure of the diet and different feeding periods to meet the needs of dairy cows and obtain the best economic benefits.