1. Reasonable Control of Concentrated Feed Consumption
The nutritive value of concentrate is higher, but it is not that the higher the proportion of concentrate in dairy cow's diet, the better. Although the nutritive value of roughage is higher, its price is correspondingly higher. If the proportion of concentrate in the diet is too high, on the one hand, it will lead to an increase in feeding costs, on the other hand, it will lead to material metabolic disorders in dairy cows, reduce the quality of milk products, and decrease the milk fat rate. Therefore, the proportion of concentrate in the diet should be reasonably controlled. The rumen of dairy cows is similar to a fermentation tank. When the proportion of concentrate in the diet exceeds 50%, the fermentation in the rumen of dairy cows will be inhibited, and the milk fat rate will be reduced. At the same time, the metabolism of protein, minerals, and other nutrients will be disordered, which will lead to the decline of the reproductive rate of dairy cows.
When feeding dairy cows, the supply of nutrients should be adequate, reasonable and balanced. To maximize the use of high-quality roughage, and then use the concentrate to supplement and balance the energy, protein, minerals and other nutrients in the diet, it is generally required that the consumption of concentrate per kilogram of milk per year should not exceed 350 g.
2. Adjusting Concentrated Feed Level Based on Milk Yield
The concentrated level in the dairy cow diet is not fixed, it should be determined according to the milk yield of the dairy cow. With the increase in milk production, the concentrate level in the diet should be increased. The results showed that the optimum concentrate level was 15%-18% for dairy cows with an annual milk yield of 2500-3000kg, 21%-25% with an annual milk yield of 3500-4000kg, 30%-35% with an annual milk yield of 4500-5000kg and 37%-39% for dairy cows with an annual milk yield of 5500-6000kg. For high-yielding dairy cows, even if the quality of roughage is better, it can not meet the high demand for energy for milk production. Therefore, the proportion of concentrate in the diet should be increased. Generally, the daily milk yield of dairy cows is less than 10 kg, which can be completely fed with roughage, and the concentrate feeding should be increased properly according to the milk production of dairy cows above 10kg.
3. Adjusting Concentrated Feed According to Roughage
The concentrate feeding amount in the diet should also be determined according to the quantity and quality of the roughage and juicy feed. If the quality of the roughage and juicy feed is poor or the quantity is insufficient, the consumption of the concentrate will increase obviously. For example, when hay is fed, the daily milk yield reaches 20 kg, and 250 g of concentrate is needed for every 1 kg of milk produced. When hay quality is poor, 500 g concentrate is required for each kg of milk to achieve the same milk yield. Besides, when feeding cows with high-quality hay, silage, and juicy feed, the consumption of concentrate will be less, which can reduce the consumption of concentrate in the diet and reduce the production cost of milk. Therefore, to reduce the proportion of concentrate in the dairy cow diet, the quality and quantity of roughage should be guaranteed.
Moreover, dairy cows in different seasons of the year eat different kinds of roughage and obtain different nutritional components. Therefore, the composition of concentrate should be adjusted according to the types of roughage they eat to meet the nutritional needs of planned milk production. In summer, grass resources are abundant. When the crude protein content of dry matter is more than 14%, the daily milk yield can be guaranteed to be 20 kg. At this time, the use of concentrate can be appropriately reduced or the use of cake feed with high protein content can be avoided, while the nutrients in the diet can be balanced by hydrolyzable carbohydrates and mineral feed to promote effective use of protein in dairy cows.
The concentrate is supplied to provide energy in summer. The use of concentrate should be determined according to the nutrient composition of forage. For forage with 12%-14% of crude protein and 22%-25% of crude fiber, 100-150 g concentrate should be added for every 1 kg milk production. For forages with the crude protein content of 10%-12% and the crude fiber content of more than 30%, 250-300 g concentrate is needed for each 1kg milk production. In the season of grass shortage, when feeding hay, silage and juicy feed to dairy cows, the content of cake feed should be increased to supplement and balance the deficiency of protein in the diet.
4. Determining Concentrated Feed Based on Lactation Period of Dairy Cows
Dairy cows in different lactation stages have different requirements for energy concentration in the diet, especially for high-yielding dairy cows. Therefore, to make rational use of concentrate, it is necessary to determine the appropriate amount of roughage according to the different lactation stages of dairy cows. In the early lactation stage of dairy cows, there will be a phenomenon of negative energy balance, which requires a higher concentration of nutrients. Therefore, in the early lactation stage, concentrate feeding is generally required to account for 44% to 45% of the total concentrate. Concentrate accounted for 36%-37% of the total roughage in the mid-lactation stage and 18%-20% in the late lactation stage. For each 1kg milk produced in the early lactation stage, the requirement of concentrate is 200-400 g, 160-360g in the middle lactation stage and 130-250g in the late lactation stage.
5. Problems to be Noticed in the Use of Concentrate
When using concentrate feed, dairy cows should be determined according to the structure of diet, different feeding periods and different lactation stages, to meet the nutritional needs of dairy cows, reduce feed costs and obtain the best economic benefits. In the preparation of a dairy cow diet, the use of concentrate should pay attention to some problems.
Firstly, the protein content in the diet should be appropriate, which should be kept at 16%-19%. If the crude protein content in the diet is too high, it will cause reproductive obstacles for dairy cows. Besides, the amount of degradable protein in the diet should account for 60-6-65% of the total crude protein. For high-yielding dairy cows, to increase the utilization of protein, high-quality rumen-passing protein feed should be used, or rumen-passing amino acids should be added to the diet.
When dairy cows mainly feed corn silage and maize, protective rumen-crossing limiting amino acids, such as rumen-crossing lysine and rumen-crossing methionine, should be added. When using concentrates, we should pay attention to the nutritional characteristics of various concentrates, such as the low degradation rate of fish meal in the rumen, the easy degradation of soybean meal and cotton meal proteins, and the lack of essential amino acids in grain proteins. Besides, we should pay attention to reasonable and balanced nutrition.