1. Lactation Law of Dairy Cows
High-yielding dairy cows refer to those cows with milk production of more than 6 tons and daily milk production of more than 30 kg in the whole lactation period. During the same lactation period, milk production of dairy cows varies significantly with breed, individual, health degree, body condition, age, nutrition and feeding management level. Usually, cow milk production begins to increase gradually after delivery, which reaches a peak in the second to third lactation month, then gradually decreases, and finally enters the dry period. For high-yielding dairy cows with good feeding and management, the increase of milk yield is large, the duration of lactation peak period is long, and the decline is slow.
If the cow can reach the peak lactation quickly after delivery, and the peak period can be maintained for a long time, it shows that the production performance of such cows is good and the total milk production is high. Dairy cows of the same breed have different age and parity, and milk yield is also different. Because the primipara cows have not yet reached body maturity, their lactation ability is worse than that of the multiparous cows. With the increase of age and parity, milk yield begins to increase after body maturity and development. Usually, the highest milk yield can be reached at 3-4 fetuses, and the milk production begins to decline and production performance decreases at 5-6 fetuses later. But if the feed price and the feeding management are good, the peak parity of some breeds can also last to 7-8 fetuses.
2. Feeding and management methods of dairy cows at different stages
According to the characteristics of lactation, dairy cows can be divided into the lactation periods, dry period and perinatal period. The feeding and management methods at different stages are different. The corresponding methods should be provided according to the needs of different stages. In the lactation period, especially in the peak period of lactation, the demand for nutrition is increasing. At this time, we should provide high-quality of high-energy roughage, silage maize, high-quality hay, etc. When increasing the energy concentration of the diet, we can not simply increase the concentrate feeding amount. Overfeeding of concentrate in dairy cows will lead to metabolic diseases such as rumen acidosis. The nutrient concentration of the diet can be increased by increasing the amount of fat feed.
If the proportion of concentrate in the diet is too high, the buffer can be added to neutralize the acidity of the rumen, thereby increasing milk production. High-yielding dairy cows need more calcium and phosphorus, so we should pay attention to the proportion of calcium and phosphorus in the diet. Determine the utilization of calcium and phosphorus when adding, and pay attention to the addition of effective phosphorus. When feeding grass feed, feed less in more additions should be made to avoid waste of feed. To improve milk production and quality, we can enrich the kinds of feed. In summer, we can feed some distiller's grains or brewer's grain, and in winter, we can feed some root and stem tuber feed such as carrot and beet.
To restore the cow's health and resting its milk production function, it is necessary to dry milk in time after more than 300 days of milk production. During the whole dry period, attention should be paid to controlling the body condition of dairy cows and not overfeeding. Therefore, the proportion of roughage in the diet should be increased appropriately, and the feeding amount of concentrate should be reduced, and the weight should be controlled at about 5%. At the same time, some roughage with satiety was provided to control the intake of dairy cows during the dry periods. When feeding cows in a dry period, we should not only control the quantity of feed but also control the quality of feed. The quality of feed should be good. We should not feed moldy feed, but also provide sufficient and clean drinking water. We should pay attention to not feed frozen tuber feed and water in winter, to avoid miscarriage or difficult labor of pregnant cows.
Perinatal dairy cows should pay attention to prenatal feeding and postpartum management. Cows enter the delivery room one week before delivery, which should be prepared in advance. The delivery room and bed should be thoroughly cleaned and strictly disinfected. Adjust the delivery room temperature to the appropriate temperature. Ensure adequate roughage supply one week before delivery, the concentrate can not be fed or feed a small amount, no feeding on the day of delivery. Dairy cows need to be done a good job of nursing after delivery, because a lot of water and physical energy will be lost in the process of delivery, but they can not be fed immediately after delivery. They should timely feed some warm water or nutritional solution with warm water, bran, brown sugar, and salt, then feed some hay.
To expel the placenta and lochia as soon as possible after delivery and promote the recovery of the body, the cow should stand up as far as possible after delivery. Cows lose nutrients quickly after childbirth and milk production, but their appetite has not been restored and their intake is small. As the demand for nutrients for milk production and body recovery increases, there will be a negative balance of nutrients, which can increase the nutrient concentration of the diet so that they can get more nutrients even if fewer feeds are taken.
Dairy cows should not be fed too much at one time after parturition. We should gradually increase the feeding amount. The feeding amount of concentrate on the first day should not exceed 2.5 kg, and then increase the feeding amount by 0.5 kg per day, and reach 6-6.5 kg on the seventh day. They can be fed normally after 2 weeks. It can not be a one-time milking net in postpartum, otherwise easy to occur postpartum paralysis. Postpartum dairy cows need to be done a good job of breast care, you can use warm water to scrub and massage breasts to reduce edema, but can not feed juicy feed, otherwise, it will aggravate edema.
3. Feeding and management of dairy cows
Strengthen the daily management of dairy cows and provide a suitable environment. Dairy cows are not heat-resistance, we should maintain the appropriate temperature of the cowshed. The most suitable temperature for dairy cows is 12-18℃. We should do a good job of heat prevention and cooling to prevent heat stress in summer and to prevent frostbite of breasts in winter, we can put on the special bras for dairy cows. It is necessary to maintain proper humidity, strengthen ventilation, keep fresh air and change cushions frequently. We should do a good job of cleaning the shed every day, and regularly disinfect the shed, column, material trough, water tank, and tools. Keep the cowshed quiet. Arrange reasonable rest and exercise time of dairy cows and keep enough exercise to enhance physical fitness, promote metabolism and promote lactation of dairy cows. Brush the cattle twice a day to remove the dirt on the body surface. Keep the cattle clean can promote metabolism, improve blood circulation, and also play a cooling role in summer.
Knowledge of Dairy Cows Feeding and Management
I.Breeding technology of dairy cows
1. Calf breeding. One hour after calf birth, colostrum was fed, and a week later, feed (starter) and high-quality hay were fed. The starter was prepared according to the proportion that 30% of corn, 25% of wheat bran, 30% of soybean meal, 2% of salt, 2% of calcium bicarbonate and 1% of baking soda. The calves were allowed to feed freely. The calves were given clean drinking water in the calf shed to let the calves drink freely. The internal temperature is maintained in the range of 10 ~24℃, the concentrate feed is consumed by about 1 kg per day for weaning at 60 days old, and the concentrate of weaned cows is increased to 1.5-2 kg per day. The high-quality roughage is freely eaten, and the young cows are fed after 7 months old.
From weaning to 30 months of age, young cattle are fed on the principle of giving priority to green roughage and supplemented by concentrate, and attention should be paid to the supply of vitamins and minerals. Adult cows are fed in three different stages: dry period, perinatal period and lactation period.
(1) Dry milk period.
Pregnant cows stop milking about 60 days before the due date, which is called dry period. Few or no juicy green fodder is fed a few days before dry milk. Drinking water is controlled and roughage is increased. A dry emulsifier is injected into four nipples after the last milking and no milking is given after a medicinal bath. If the breasts become red, swollen, hot and painful, the second dry milk or dry milk after the treatment depending on the situation
(2) Perinatal period.
Increase concentrate feeding gradually from 15 days before delivery. The ratio of concentrate to roughage is 40:60. Attention should be paid to low calcium before delivery and high calcium after delivery to prevent postpartum paralysis. Feeding easily digestible and palatable fodder after delivery. Milking for the first time of 1 - 2 hours after delivery should not be too much, as long as it is enough for calves to eat, and gradually increase every day, until the third day to squeeze the breast milk.
(3) Lactation period.
It is a concentrate which increases by 1-20% during the peak lactation period, especially for the first and second-born cows. The second is the mid-lactation period (101-200 days after delivery), and the ratio of concentrate to roughage is 50:50, and crude fibers not less than 17%. The third is a late-lactation period(201 days to dry milk), the ratio of concentrate to roughage is 40:60, crude protein is 12%, and crude fiber is not less than 18%.
II. Management measures for dairy cows
Cows of different ages, types, and levels of production are fed in groups with different feed formulations and feeding quantities. The feed of dairy cows is roughened first, then concentrate, or can be fed with a full mixed diet, that is, the mixture of roughage and concentrate, silage and various additives which are cut short (about 2.5 cm) will be fully mixed and fed. Adequate and clean drinking water is provided every day and cattle keep adequate outdoor exercise. Attention should be paid to preventing heat and cooling in high-temperature season and keeping warm and preventing colds in the cold season in the cowshed. Feed supply and feeding management should be adjusted timely according to fatness. Estrus performance and status should be observed every day, and timely breeding should be carried out. Correct and hygienic milking operation habits should be maintained, to avoid mastitis and ensure the hygiene of raw milk.
Ⅲ. Reproduction and breeding of dairy cows
Dairy cows usually have their first estrus when they reach the age of 8-12 months and 45% of the body weight, which are called the first estrus period. They reach sexual maturity at the age of 12-14 months, and their mating age is 16-18 months. Only when the bodyweight reaches 70% or 375 kg per year can the mating be completed. The cows were first mated 18-10 hours after oestrus, and the second mated 8-12 hours after oestrus. Dairy cows have an average estrus cycle of 21 days, and cows that have been estrus but not mating or have been mating but not pregnancy would begin the next estrus cycle in about 21 days. If no estrus occurs in two consecutive estrus periods after mating, they should be regarded as pregnancy. They can go to the improved site for pregnancy examination at three months. The average gestation period is 280 days, which can be used to estimate the expected delivery date.