How to improve the feeding management of milk fat and protein content

The factors affecting milk fat and protein content include heredity and environment. Environmental factors include lactation stage, milk yield, age, disease and nutrition. About the change of milk composition is caused by environmental factors. Generally, when the ratio of milk protein / milk fat decreases, it indicates that the content of milk protein is low, while when this ratio indicates that the rate of milk fat is low. The feeding and management factors affecting the content of milk fat and milk protein include:

（1） Feed intake

Increasing feed intake can increase the content of milk fat and milk protein, and the increase of feed intake can increase the content of milk protein. The dry matter intake of high-yield dairy cows is lower than that, that is, the reduction of milk solids may occur.

（2） Concentrate feed rate

Appropriate concentrate feed can increase the content of milk fat and milk protein. Too high concentrate feed will lead to the decrease of milk fat rate, but the content of milk protein may increase slightly. From the perspective of milk fat and milk protein content, the diet is low in fiber concentrate. The amount of concentrate fed each time, the total amount of concentrate per day, and the proportion of concentrate with the increase of milk production depends on the range of milk production.

（3） Roughage feed rate and particle size

The ADF level and NDF level of diet caused the decrease of milk fat rate. The particle size of roughage for dairy cows should be no less than one centimeter. Too fine roughage reduces the milk fat rate and the milk protein level may increase slightly.

（4） Dietary protein level

Increasing the crude protein level of diet generally does not affect the content of milk protein, but the milk yield may be increased. If the level of crude protein in the early diet is insufficient, the content of milk protein can be increased. Excessive rumen degradation protein may also reduce the content of milk protein. Therefore, there should be a certain proportion of rumen protein in the diet of lactating cows, and the proportion of rumen protein in the diet in the early lactation stage in the proportion of crude protein. Urea shall be added after four months of milk production, and the proportion shall not exceed the mixed concentrate.

（5） Add fat

It is usually necessary to add fat to the diet of high-yield dairy cows to reduce the negative energy balance in early lactation. With proper addition method, the milk fat rate increased slightly or remained unchanged, the milk protein did not decrease significantly, and the milk yield increased. Improper addition may reduce the content of milk protein. Daily administration of nicotinic acid can correct the decrease of milk protein caused by fat addition. Only high-yield dairy cows in early lactation were added with fat, and the levels of dietary calcium and magnesium were increased to dietary dry matter at the same time.