Silage is fermented by lactic acid bacteria in green feed under anaerobic conditions, so that part of sugar sources in the feed are converted into lactic acid, and the pH value of the silage is reduced to below 4.2, thereby inhibiting the reproduction and growth of other aerobic microorganisms such as molds and spoilage bacteria, and achieving the purpose of long-term preservation of green feed. The mechanism of silage fermentation is a complex process of microbial activity and biochemical changes. Its duration is about 3 weeks, which can be roughly divided into five price segments: the first price segment is the stage of creating an anaerobic environment. From the time silage was put into the cellar, plant cells kept breathing. Some people call this period the plant respiration period. The respiration period of high-quality silage plants is about 3 days. As a result, carbon dioxide and heat are produced, which makes silage gradually become an anaerobic environment. Coupled with heat production, it provides conditions for the reproduction of lactic acid bacteria. If the air in the gap between silage is not compacted and discharged, it will not only prolong the breathing period of plants, but also cause the loss of nutrients. The second stage is mainly the stage of producing acetic acid. The increase of acid concentration creates conditions for lactic acid bacteria to start reproduction. The third stage is that lactic acid begins to produce valence bands. It is also the stage where Acetobacter can't survive in high acid and is limited. The above three price segments take about 5 days, and they are interspersed with each other without certain boundaries. The fourth valence band is the valence band of lactic acid bacteria proliferation and lactic acid formation. Under normal circumstances, the temperature in the cellar dropped from 330C to 250C, and the pH value dropped from 6 to about 4.0 (the pH value of silage: 3.8 ~ 4.4 is good; Moderate is 4.5 ~ 5.3; Bad 5.4 ~ 6.0). This price range lasts 15 ~ 20 days. Because the lactic acid produced reached the highest level, lactic acid bacteria themselves were also inhibited. The fifth stage turns to a stable stage after 1 month, which depends on the first four valence stages. First of all, if the amount of lactic acid and acetic acid produced is sufficient, the influence of other miscellaneous bacteria can be prevented. Otherwise, the amount of lactic acid is small, and harmful bacteria will multiply in large numbers; Butyric acid bacteria will produce butyric acid, which will act on silage raw materials to cause decomposition, so that protein and amino acids will be decomposed into ammonia and amine, and silage will produce odor and affect palatability. Secondly, if the silo is tightly pressed, the exhaust is clean, and the top is tightly sealed without air leakage (it sinks the most in the first few days, and the top should be covered with soil in time after sinking), the silage can be stored for more than 10 years. Otherwise, once the air enters, it will be oxidized and heated, causing losses; At the same time, in the presence of air, mold can reproduce, and lactic acid produced in the fourth stage can be utilized, so that after the acidity is reduced, miscellaneous bacteria multiply in large numbers, causing silage to be moldy and smelly and suffer losses.

The key to the success of silage lies in whether it can meet the four conditions for the growth and reproduction of lactic acid bacteria: anaerobic environment (oxygen oxidizes feed, which makes aerobic microorganisms such as molds and spoilage bacteria multiply in large numbers and cause corruption. The method is to compress waste gas to form anaerobic environment), add enough sugar in raw materials, add appropriate water content (65 ~ 75%), and pay attention to temperature. The most suitable temperature is 25 ~ 30 degrees, and it is not a big problem to control it between 19 ~ 37 degrees. All four are indispensable.

First of all, in order to ensure the anaerobic environment, the green materials should be cut short, cellar-loaded, compacted and sealed as soon as possible after harvesting, which is the premise of maintaining low temperature and creating anaerobic conditions. Cutting is to facilitate compaction, compaction is to exclude air, and sealing is to isolate air. Otherwise, if there is air, plant cells will continue to breathe, and the pit temperature will rise, which will not only be detrimental to the reproduction of miscellaneous bacteria, but also cause a large loss of nutrients.

Secondly, in order to ensure the proliferation of lactic acid bacteria, it is necessary to have appropriate sugar content. According to the sugar content of feed, silage raw materials can be divided into three categories: the first category is easy silage with high sugar content, such as corn stalk, Jerusalem artichoke, sunflower, carrot stem and leaf, turnip, forage cabbage, gramineous grass, sweet potato vine, pumpkin and so on; The second category is the raw materials with low sugar content, such as alfalfa, clover, sweet clover and other leguminous grasses, as well as the stems and leaves of soybeans, peas and potatoes. This raw material should be mixed with the first one. The third category is raw materials that cannot be silaged separately, such as pumpkin vines and watermelon vines. The sugar content of these plants is extremely low, so they can only be mixed with other raw materials that are easy to silage, or with corn flour and other carbohydrate-rich feeds, or with acid in silage (including, for example, adding 1kg propionic acid per 100kg silage raw materials, but care should be taken to prevent splashing on the skin; Or adding a.i.v. diluent (consisting of 192 parts of 30% hydrochloric acid, 8 parts of 40% sulfuric acid and 800 parts of water) into 5-6% of raw materials; Or adding A. A Z diluent (liquid is formed by mixing 170 parts of hydrochloric acid with a concentration of 8- 10% and 30 parts of sulfuric acid with a concentration of 8- 10%) according to 5-7% of the raw materials; Formic acid and formic acid can also be added (the effect is better than hydrochloric acid and sulfuric acid, because strong acids such as hydrochloric acid are easy to dissolve calcium salt and affect the absorption of calcium). Because formic acid can be decomposed into carbon dioxide and methane which are harmless to livestock during silage or rumen digestion, formic acid itself can also be absorbed and utilized, and the weight gain effect is higher than that of general silage. The dosage is 2.85 kg (UK) or 4.53 kg (USA) of 85% formic acid per ton of raw materials. Advantages of acidified silage: green color, rich fragrance and excellent quality (protein loss is only 0.3~0.5%, while general silage loss is1~ 2%; Crude fiber is reduced more; Less loss of carotene, VC, calcium and phosphorus).

Thirdly, the appropriate moisture content in silage is an important condition to ensure the normal activity of lactic acid bacteria. The optimum water content is 65 ~ 75%. 60 ~ 70% leguminous forage is the best. In addition, there are differences due to different textures. The water content of coarse and hard raw materials can be as high as 78 ~ 82%; However, the moisture content of raw materials harvested early, tender, juicy and soft is lower, and 60% is appropriate. Silage raw materials with too high or too low water content should be cooled or adjusted with water. If it is too high, it should be slightly cooled and withered before storage. If it still doesn't work, it can be mixed with crushed hay or straw for silage. The method of judging and observing water content mainly depends on the experience in production besides the actual measurement. First, hand extrusion method: grab a chopped silage raw material and squeeze it hard for 30 seconds. When you open your hand, water will flow out or through your fingers. The water content is about 75-85%, which is too wet to make high-quality silage. You should dry it in the sun, or silage it with dry straw, or add 90 kilograms of corn flour or rice bran and wheat bran straw powder per ton. If the dough is spherical when wet, the water content is about 68 ~ 75%, or the dough is slowly dispersed when wet, and the water content is about 60 ~ 67%, which is the best water content for silage without any additives. If the dough is scattered immediately after opening the hand, and the water content is lower than 60%, it can only be silaged after adding water. 2. Kneading method: Before chopping, the stalk of the straw is not broken, the leaves are soft and green but not dry, and the water content is the most suitable. Generally speaking, leguminous plants should be harvested and silaged in time when the water is suitable at bud stage and early flowering stage, gramineous plants at booting stage and heading stage, and corn at milking stage.

4. Suitable temperature. Generally controlled between19 and 35 degrees. But the most suitable temperature is 25 ~ 30 degrees. If the fermentation temperature is lower than 350℃, the fermentation time is 10 ~ 14 days. The fermentation time is 13 ~ 20 days at 35 ~ 450℃. When the temperature is higher than 450℃, the fermentation time is 17 ~ 22 days, but the silage fermented at high temperature is easy to deteriorate.

There are five silage methods: bag storage, tower storage, heap storage, ditch storage and cellar storage.

Bagged silage: cut the silage raw materials into small pieces, put them into plastic bags, exhaust and compact them, and then tie them. If the bag length, width and height are 1m and 2.5m respectively, each bag can hold 750 ~ 1000kg of corn silage. The thickness of plastic film is greater than 1mm, and it can be used for 2 years. However, it should be placed away from sharp tools such as animals and farm tools to prevent biting, scratching and cutting, so as not to affect the quality of silage.

Heaping silage: level the ground with cement, then pile the chopped green materials together, compact them, cover them tightly with plastic film to make them airtight, and compact them with heavy objects such as soil. However, this method can not ensure the tight filling of raw materials, so the quality is often poor. If the whole silage pile is wrapped and sealed with plastic film, and then the air is pumped out to make the so-called vacuum silage pile, the effect is quite good.

Pit silage: there are two kinds of underground silage and semi-underground silage, and underground silage is widely used. If the groundwater level is high, in order to avoid water seepage at the bottom of the pit, semi-underground method is better. The periphery of the permanent silage cellar is made of brick or stone, plastered with cement, airtight and watertight, and the inner wall is smooth and vertical, or bucket-shaped or inverted trapezoidal. The advantage of barrel or inverted trapezoid is that after the raw materials are filled, the raw materials can sink by themselves under the gravity of the feed itself, which is beneficial to exhaust the air around the cellar wall and reduce the loss of silage around the cellar wall. Silage silos in large dairy farms are generally required to be more than 3 meters deep and 4 ~ 6 meters wide, with different lengths depending on the number of dairy cows (1 cubic silo can store 450 ~ 700 kilograms of green fodder. Average 550kg). In order to prevent rainwater or surface water from flowing into the pit, the pit mouth should be 0.2 ~ 0.5 meters above the ground. But one end is connected to the sloping ground.

Ditch silage; A long ditch, the two ends of the ditch are inclined, and the bottom and both sides of the ditch are leveled with concrete. Build two flat cement walls on the flat ground, and there is a silage ditch between the two walls, which is generally 2-3 meters wide, 4-5 meters wide and 20-30 meters long, depending on the terrain, needs and raw material quantity.

Tower silage: It is a tower-shaped building made of steel bars, bricks and cement. The advantages are that the silage tower is durable, the silage quality is high, and the nutrient loss is less, and the raw materials are all made by special machinery. The disadvantage is that the investment is large and it is only suitable for large cattle farms. The inner diameter of the tower is generally 5 ~ 9 meters, and the tower body is 9 ~ 24 meters. A window about 60 cm square is opened every 2 meters on one side of the tower for taking materials. There are also sealed silage pits abroad. The tower body is made of metal and glue, which is completely sealed. The top is equipped with a breathing bag to facilitate the expansion and contraction of the internal gas. This machine is used to take materials from the bottom and can control loading, unloading and feeding.

Before filling, a layer of 10 ~ 15 cm thick broken straw or grass can be filled at the bottom of the cellar to absorb silage juice. Straw can be cut into 3cm, and grass, sweet sorghum, Sudan grass and vines can be as short as 10 ~ 20cm, and then directly put into plastic bags or green storage tanks, and each layer should be stamped repeatedly to exhaust. Pay special attention to the compaction around the pit wall and the corner until it is filled and exceeds the pit mouth by 20cm, then cover it with thick plastic sheets and compact it with wet soil. Check frequently in the first few days after sealing, and fill in the soil in time if settlement and cracks are found. In order to keep warm in winter, you can spread some corn stalks on it.

Access time: It is reported that the cellar can be opened for access after lactic acid fermentation for at least 265,438+0 days in summer under the condition of properly silage raw materials with high sugar content. But general silage can complete the whole fermentation process within 30 ~ 45 days. The softer the raw material, the shorter the fermentation time (about 40 days); Conversely, the harder the material, the longer the fermentation time (about 45 ~ 50 days). It takes 5 ~ 6 weeks to silage easily with corn stalk and other sugar-rich raw materials; It takes more than 60 days for leguminous forage to be made into silage. Good silage (pH 3.8 ~ 4.4) can be stored for several years, up to 20 ~ 30 years.

Silage can't replace hay when feeding, and it is easy to cause acidosis (the PH value in rumen is weakly acidic) and the feed intake is reduced. Silage also has laxative effect, so pregnant livestock should not be fed more. The reference feeding amount (kg/ day) of various livestock silage is as follows: lactating cows15-20; 4-20 breeding cattle; Cattle10-20; Beef cattle10-20; Horse and mule 5-10; Sheep 1.5- 1.8. The feeding amount can also be determined according to the weight: the feeding amount of heifers can account for 2.5 ~ 3% of the body weight; Bull accounts for1.5 ~ 2% of body weight; Fattening beef cattle can account for 4~5% of body weight. The feeding amount of sheep can be determined by referring to the method of feeding cattle by weight. Frozen silage can only be fed after it melts.