1. Selecting breeds and individuals with high milk fat rate
For different breeds of dairy cows, there are also differences in milk yield and milk composition. Usually, the milk yield and milk fat rate of dairy cows are negatively correlated, that is to say, the higher the milk yield of dairy cows, the lower the milk fat rate. For example, Holstein cattle belong to high milk yield breed, but its milk fat rate is low, generally, 3.6% and Jersey cattle have a high milk fat rate, which can reach 5.2%, but the milk yield is relatively low. In addition, even different individuals in the same dairy cow breed are different. For example, the milk fat rate of Holstein cows can vary from 2.6% to 6.0%. Therefore, we must pay attention to the selection of dairy cow breeds and individuals in order to improve the milk fat rate.
2. Adjusting the ration structure
Adjust the proportion of concentrate and roughage in dairy cow's diets to increase the level of dry matter in the diet, especially the intake of crude fiber. To make the ration of dairy cows have a reasonable proportion of concentrate and roughage, and eat more dry matter, it is necessary to pay attention to the scientific processing and regulation of roughage, especially the quality of straw feed and silage. According to the calculation of dry matter, the proportion of concentrate and roughage in the diet of dairy cows should be controlled above 40:60 and below 60:40, and it should be adjusted timely following the level of milk production.
The best way to feed dairy cows is to let them eat roughage or feed roughage first and then concentrate, changing the traditional habit of feeding a large amount of concentrate first and then forage. When dairy cows adopt free forage intake, for those with daily milk production of 20 kg, they should control feeding less than 8 kg of concentrate; daily milk production of 20-25 kg, concentrate feeding of 8-12 kg; daily milk production of more than 25 kg, concentrate feeding of about 13 kg, but can not exceed that level. The feeding amount can also be determined by feeding concentrate 300 g per kg of milk produced by dairy cows, or by the feeding-milk ratio of 1:(3.0-3.3).
3. Rational use of additives
Dairy cows can increase their energy intake without increasing grain feed by adding fat in their diets. Adding fat to the diet of dairy cows can increase milk yield and milk fat rates at the same time. For example, adding protective fats or whole rapeseed to dairy cow diets can often increase the milk fat rate by 0.1%-0.2%. When the fat content in the dairy cow's diet was 5%-6%, the utilization rate of various nutrients could reach the highest. If the proportion of concentrate in dairy cows' diet is too high and the content of crude fat is less than 3%, it is necessary to add 3% protective fat or 3% cottonseed to increase the milk fat rate.
Adding nicotinic acid to the diet of dairy cows can not only increase milk yield by 2.3%-11.7% but also increase the milk fat rate by 2.0%-13.7%. Adding 7 g of carotene preparation to the diet 30 days before and 92 days after dairy production could increase the net milk yield by 200 kg per lactation period, and the vitamin A level in milk increased by 21.5%. Adding vitamin E to the diet of dairy cows can enhance their immunity, increase their milk production, inhibit fat oxidation in milk, delay the fatty acid deterioration time of milk and increase the storage time.
For high-yielding dairy cows, the need to ensure adequate energy intake often limits the intake of roughage. In this case, adding the appropriate amount of sodium diacetate or sodium acetate to the feed of dairy cows can improve and promote the balance of electrolytes internal, thus stimulating the liver, kidney, and intestinal mucosa, thereby increasing the milk fat rate. It is reported that adding sodium acetate to the diet of dairy cows can increase milk yield by 5.58% and milk fat rate by 10.58%. At the same time, it can alleviate heat stress in a high-temperature environment of dairy cows. Usually, 300 g per cow per day is enough.
4. Strengthen daily management
Prevent heat stress.
When dairy cows are in the high-temperature environment of over 30 ℃, they are prone to heat stress reaction, which leads to the reduction of milk yield and milk fat rate. Therefore, we should pay attention to and strengthen the work of heat prevention and cooling to create a comfortable and cool feeding environment for them. You can choose to build shade in the playground, install spraying facilities and fans in the shed, to reduce the environmental temperature.
Milking operation specifications.
An important way to improve milk yield and milk fat rate of dairy cows are to take proper massage and milking operation on their breasts. Before milking cows, first wipe the breast with warm water to stimulate breast vasodilation to increase the flow of blood to the breast, which can promote milk fat synthesis. Besides, milk from different parts of the breast of dairy cows has a different milk fat rate. For example, milk in the milk pool contains only 0.8%-1.2% of milk fat, while milk duct contains 1.0%-1.8%, and breast acinus contains 10%-12%. Therefore, when milking cows, we should try our best to clear the milk in the breast acinus, which can not only increase the milk fat rate by 0.2%-0.4% but also increase the yield by 10%-20%.
Strengthen management during the dry periods.
The dry period of dairy cows is not only a stage in which the fetus needs more nutrients for rapid growth and development but also a stage that lays a good foundation for the next lactation period to be more durable and better lactating. Because the mammary gland of dairy cows has ceased to secrete during the dry period, it is necessary to improve the nutritional status of dairy cows in time and adopt scientific feeding management.