After the calf was born, its living environment suddenly changed. At this time, the calf's tissues and organs are not fully developed, and its adaptability to the external environment is poor. Because of gastrointestinal emptiness, lack of secretory reflex, extremely inactive digestive enzymes, no mucus on abomasum and intestinal wall, bacteria easily cross into the blood to cause disease; The skin protection function of newborn calves is also poor, and the nervous system is not perfect, which is easily affected by external factors and leads to diseases and even death in severe cases. In order to reduce the incidence of calves and cultivate healthy calves with normal development, they must eat colostrum well, because colostrum has the following characteristics and functions: ① It can replace the mucus on the gastrointestinal wall to some extent, cover the inner surface of the gastrointestinal wall and prevent bacterial invasion. ② The high acidity of colostrum can make gastric juice acidic, which is not conducive to bacterial reproduction; Colostrum contains lysozyme and antibody protein, which can be absorbed by the intestinal chorion of newborn calves, so that calves can gain disease resistance. (3) Colostrum has a high nutritional concentration, which can meet the characteristics of small intake and relatively high nutritional requirements of calves.
With the increase of lactation days, the nutritional composition and characteristics of colostrum are constantly changing. Generally, after 6 ~ 8 days, the composition of colostrum is close to that of normal milk (see the table below). Moreover, the physiological characteristics of gastrointestinal tract of calves also change with age, and the absorption rate of antibodies in colostrum decreases rapidly. Therefore, calves should be fed full colostrum as soon as possible. Usually within 2 hours after birth, when the calf stands up, it can be fed colostrum. The feeding amount of colostrum is generally 6 ~ 8 kg per day, and it is fed 3 ~ 5 times. When feeding colostrum, we should pay attention to feeding it immediately after squeezing to prevent colostrum from deteriorating in summer and reduce its temperature in winter. If the temperature of colostrum is too low in winter, it can be heated to about 36℃ through water before feeding calves. The heating temperature should not be too high, otherwise colostrum will coagulate and calves may refuse to eat.
Comparison of components between Holstein colostrum (within 24 hours after birth) and normal milk (unit:%)
The composition of normal milk fat is 5.4 3.5 protein 14.3 3.25 albumin10.50.47 immunoglobulin 5.5 ~ 6.8. 0. 09 ash 0.97 0.75 calcium 0.26 0. 13 magnesium 0.04 0.0654438+0 phosphorus 0.2438.