Since the dry matter intake of dairy cows in the late pregnancy (dry period and perinatal period) is greatly reduced, energy intake is seriously insufficient in the early stage of lactation. After the cows have calves, they start to produce milk. The nutrient needs rise rapidly, the digestive function begins to recover slowly, and the dry matter intake gradually increases. However, the rate of recovery and rise is very slow, far below the rate at which nutrient needs rise. As a result, the increase in feed intake lags behind the peak of increased milk production, resulting in a metabolically negative balance of cows, especially in high-yield cattle. The result of negative energy balance eventually leads to a decrease in milk production during the peak lactation period, a shortened period of time during peak period, and a cow's milk production potential cannot be fully utilized, resulting in a significant drop in milk production throughout the entire fetus. At this time, the cows use body fat to meet the energy needs of the milk, and the cow's weight is reduced. A large amount of body fat is used to produce milk, which greatly increases the risk of fatty liver and even ketosis in cows.
1 Methods and measures to improve the energy of dairy cows
1.1 increase animal feed intake
Improving the palatability of the diet and increasing the appetite of the cow can alleviate the problem of low energy intake of postpartum cows to some extent. However, the recovery of digestive function of postpartum cows is a process that takes a certain amount of time. Therefore, the extent of solving the above problems through this route is limited, and the problem cannot be completely solved.
1.2 adjust the ratio of coarse and fine feed
It is common to increase the proportion of concentrate in the diet to increase the energy concentration of the diet, but it will bring about problems such as decreased fiber digestibility, decreased milk fat, rumen dysfunction, bloating and ketosis.
1.3 Add high energy feed
Adding fat to the diet to increase energy in the diet has become an effective measure. Foreign studies on fats and oils as feed additives for ruminants are more and more gradually applied in animal husbandry production. There are currently few domestic information on the development, development and application of such products. Therefore, in order to open up new fields of domestic ruminant energy-based feed additives, many domestic research institutions have begun to develop new high-energy feed additives. This paper describes the research results of dairy cow high energy feed additives at this stage.
2 cow high energy feed additive
2.1 fatty acid calcium
The added fat is not protected in any form and can be destroyed by the rumen of the ruminant, hindering the activity of the rumen microorganisms and reducing the cellulose digestibility. Therefore, the fatty acid-calcium fatty acid which is combined with a fatty acid and a calcium salt cannot be fully utilized because a long-chain fatty acid is liable to form an insoluble substance. The main role of fatty acid calcium is to increase milk production, improve milk quality, prolong lactation, and reduce heat stress. Disadvantages: Fatty acid calcium has a slight odor and must be mixed with other feeds when feeding, maintaining a transition period of 5-7 days.
2.2 corn crude oil and soybean phospholipid
The addition of corn crude oil and soybean phospholipids to dairy cow diets can significantly increase milk production in dairy cows. This is because high-yield cows increase their energy requirements during the early lactation because of the need for lactation, while the increase in dry matter intake is limited, so by adding corn crude oil and soybean phospholipids to the diet. The energy concentration of the diet increases the energy to meet the cow's energy needs, increases the digestibility, and increases the milk yield of the cow. In recent years, soybean phospholipids have been used as feed additives to replace some fats. They have been initially used in the feed industry, and have achieved good economic and social benefits. They have solved the problem of comprehensive utilization of by-products for oil plants and provided high quality for feed mills. additive. Disadvantages: It was found that the corn crude oil was poorly palatable and reduced the feed intake. If processing can be taken, the situation can be further improved.
2.3 hydrogenated fat powder
Hydrogenated fat powder is a rumen protective fat. It has been researched and developed at a later time than fat calcium soap. It is a new type of fat product for ruminant feed in the world. The processing principle is that a physic method is used to fractionate the fatty acid in the raw material according to its melting point, and the collected high melting point fatty acid is processed. Compared with fatty acid calcium soap and hydrogenated fat powder, rumen-stabilized fat powder has the following advantages: high fat content, high effective energy content, and higher than fatty acid calcium soap. Most of the fatty acids contained are saturated fatty acids, which are stable in the rumen and have a good rumen effect. The low melting point reduces water solubility and thus does not affect the activity of the microorganisms and the digestion of the crude fibers in the rumen. Compared with fatty acid calcium soap, hydrogenated fat powder has the advantage of a significant increase in fat content. The results of Zhuangsu and other experimental data show that adding fat powder can increase the milk yield by 5.6%, and the standard corrected milk is 7.3%, which has little effect on the content of milk protein and lactose. In addition, there is no uniform standard for the addition of fatty acid calcium in China. It is generally believed that the amount of addition should be determined according to the energy level and crude fat content in the animal diet. Therefore, the focus of future research should focus on different energy levels, and the amount of addition should also be It should be different.
2.4 high oil corn
High-oil corn not only has much higher oil content than traditional corn, but also has higher content of protein, lysine, vitamins and trace elements than ordinary corn. It is a high-quality and high-energy food, feed and industrial raw material. In the United States, high-oil corn is called "value-added corn." The conclusion of the Ti Rigen Bai Bila test: the use of high oil corn increased the number of rumen ciliates in dairy cows, which had a certain effect on the leaven. The increase in the production of lactose and milk protein also increases the production of fat-free solids in the milk, which has a positive effect on improving the fat-free solids as a component of the intermediate milk. The proportion of fatty acids in the milk fat was also significantly changed, but the milk fat percentage decreased slightly.
2.5 alcohol
Alcohol as a supplement to energy, in high-yielding lactating cows, can reduce costs and improve animal quality. In the case of insufficient energy, the protein is converted into energy by the cow, but this is a high energy loss and inefficiency. Foreign reports that adding alcohol to the feed can increase the weight gain of the cow, increase the milk yield, and increase the milk fat percentage. However, the specific addition amount will be added due to animal differences and feed differences.
2.6 oils and fats
Oils include: peanut oil, olive oil, soybean oil, rapeseed oil, peanut oil, sunflower oil, sesame oil, corn oil, coconut oil, palm tung oil, palm tung oil, butter, lard, fish oil, flax, butter, Castor oil, in which vegetable fats account for 75%, animal fats account for 25%. In addition to butter, animal fats are mainly based on butter and lard. In recent years, the application of oil as an energy feed in animal diets has received more and more attention. The use of oil and fat as a supplement for dairy cows also ensures the supplementation of cellulose and improves the breeding machine to maintain a high peak of lactation. The pregnancy rate of cows supplemented with fat is 2.22 times that of non-fat cows. As a fat additive, for the production and processing of feed, less dust is generated, which reduces air pollution in the workshop.
(1) Researchers in the United States, Canada and other countries have carried out experiments on the production performance of dairy cows such as sunflower seeds and soybean meal as energy supplements. The result is that the number of rumen microorganisms is reduced, the pH is lowered, and cellulose is The digestibility is reduced. Cow et al found that when the fat in the diet was deficient, the C16:0 content in the milk increased and the C18:0 and C18:1 decreased. Feeding the high-fat diet reduced the proportion of C16-C18 fatty acids in the milk fat, while C18:0 And the C18:1 content is increased.
(2) Conjugated fatty acid-(conjugated linoleic acid) is added to the diet, which has an effect on the milk yield and milk fat percentage of dairy cows. According to the experimental results: the milk volume increased by 9.19%, and the milk fat percentage decreased by 14.08%, but the mechanism of lowering the milk fat percentage is not fully understood.
(3) Animal fats, such as butter and lard, contain more than 40% saturated fatty acids, which have less effect on the digestion of rumen fibers. Because of its high saturated fat content, butter has a melting point of over 40oC. Its inconvenience is that it needs to be heated and melted before it can be easily mixed with other raw materials, but there are few studies in this area at home and abroad.
2.7 Choline Chloride
In the early stages of lactation, effective supplementation of choline is important for saving heterologous precursors of methionine and sugar. Choline acts as a precursor to acetylcholine and is an important source of unstable methyl groups. Early studies have shown that the addition of a non-rumen protective form of choline chloride to the diet has a positive effect on milk production and milk fat percentage. It has a greater effect on the negative balance of dairy cows and has no effect on the milk composition.
3 existing problems and suggestions
Protecting the palatability of fatty feeds can affect the feed intake of dairy cows. The processing technology of hydrogenated fat and the amount of feeding should be the focus of a research. It is inconvenient to store for a long time, and it is easy to be rancid. It is also a problem that affects its wide application. The development and utilization of high-oil corn feed should increase the impact of scientific research, especially with other feeds as additives on the performance of dairy cows. Alcohol as a feed additive has not been systematically studied in China, and some farms abroad have achieved some benefits and benefits. In short, the energy feed of oils and fats has the disadvantage of containing high levels of unsaturated fatty acids, so this is an important factor affecting the performance of dairy cows. For cows fed oil-based feed, the milk contains too much unsaturated fatty acid, which causes the milk to deteriorate and become difficult to store. Regarding the feeding standards for oils and fats, China has not yet issued them. Therefore, it is extremely urgent to establish quality standards for feed fats and oils. For the development and utilization of CLA is still just beginning, should study the mechanism of its action. The mechanism of action of choline and the optimal level in the diet were not determined.
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