饲料分类英文课件ChapterSilag.ppt

Chapter 4 Silage（青贮饲料）,4.1 Introduction,(1)Definition Silage is the material produced by the controlled fermentation of a crop of high moisture. Silage may be defined as fermented forage plants.,(2)History of silage It is a very old method of preserving feed. Columbus found that the Indians used pits or trenches in which to store their grain, and , centuries earlier in the Old World, silos were used as a means of preserving both grain and green forage. The first tower silo built in the USA by the white man is said to be erected by F. Morris in Maryland in 1876.,4.1 Introduction,(3)The reason of making silage Silage making is one of the 3 common methods of utilizing forage crops. Pasturing is the least expensive of the 3 methods, but it is seasonal in nature. Weather condition are not always favorable to haymaking. Ensiling can be done in inclement weather. Also, it has the added virtues of succulence and of preserving a higher proportion of the nutrients of the plants than can be accomplished in haymaking.,4.1 Introduction,(4) Haylage (low-moisture silage，半干青贮) Haylage is made from grass or legume that is wilted to 40%-55% moisture content before ensiling. It is similar to silage except it is lower in moisture. Properly made haylage has a pleasant aroma and is a palatable, high-quality feed. Animals usually receive more DM and net feed value in haylage than in silage made from the same cut.,4.1 Introduction,(5)Kinds of crops used for silage Practically any crop may be made into silage, provided it contains : An appropriate level of moisture Adequate amounts of readily fermentable carbohydrates Adequate levels of other nutrients Provided it can be packed sufficiently Corn Most extensively used silage crop. Corn silage is unexcelled in quality.,4.1 Introduction, Forage sorghum Most are very high yielding but do not produce the best silage. It inclined to contain excess water and acid, hence is not very palatable or nutritious. Grain sorghum Grain sorghum silage is between corn silage and forage sorghum silage in palatability. Higher DM content.,4.1 Introduction,4.2 The ensiling process,4.2.1 Aerobic activity The living plant cells of the forage continue to respire. The plant forage carries with it a large number of aerobic fungi and bacteria. The activity of aerobic microorganism gradually ceased with the development of anaerobic conditions. Aerobic yeasts and molds thrive and multiply.,4.2.2 Anaerobic activity Yeasts and molds die. Anaerobic bacteria, chiefly acid-forming and proteolytic（蛋白质分解的）, multiply at a prodigious(惊人的） rate. These bacteria, or enzymes produced by them, and enzymes from the cut plant material, attack the sugars and other material, breaking them into organic acids, principally lactic, acetic（乙酸） and formic（甲酸）, some ethyl alcohol(乙醇）, some gases like CO2, CH4, CO, NO, NO2.,4.2 The ensiling process,4.2.2 Anaerobic activity Much of sugars is changed to organic acids, and some of it is used for the bacteria and is built up into compounds in their bodies. Small quantities of the proteins are broken down into ammonia, amino acid, amines（胺）, and amides（酰胺）.,4.2 The ensiling process,4.2.2 Anaerobic activity Some of the proteins are broken down into AA, but in badly preserved material the AA are broken further to various amines such as tryptamine（色胺 ）, putrescine（腐胺 ）, histidine（组氨酸） , phenylethylamine（苯基乙醇胺 ） etc., which at higher concentration may be harmful to the consuming animals. Yeasts, followed by molds, will again become active if silage is exposed to air.,4.2 The ensiling process,4.2.3 Optimum pH The acidity finally reaches a point where the bacteria themselves are killed and the silage-making process is completed. The formation of a pH of 3.5-4.5 is the key to good wilted silage preservation. Excellent low-moisture silage (45-60% moisture) is frequently made in the pH of 4.0-4.5, and even up to 5.0.,4.2 The ensiling process,4.3 How to make good silage,Using a sound silo of proper size. Harvest at the proper stage of maturity Cut to proper length Control the moisture content An additive or preservative when needed Fill rapidly Distribute forage uniformly in the silo Seal or top-off the silo.,4.3.1 Harvest at the proper stage of maturity The crop for silage making is generally harvested at the flowering stage when it has the maximum amount of nutrients. When cut at the proper stage of maturity, corn and sorghum forage possess just the right amount of sugar for the production of good silage. If cut when too immature, these crops, being high in sugar and water, may cause excessive acid formation and result in an unpalabable.,4.3 How to make good silage,4.3.1 Harvest at the proper stage of maturity Silage materials containing less than 25% DM (more than 75% moisture ) will form very sour silage. Plants for silage making may be allowed to mature till the DM content attains 35-40%.,4.3 How to make good silage,4.3.1 Harvest at the proper stage of maturity (1)“Black layer test” can be applied quickly and easily to determine when to harvest corn for maximum yield and nutrient quality. The grains are dented（凹痕） and glazed（光滑明亮）. The lower 4 to 6 leaves of the corn plant are brown. The plant contains 60-67%moisture. It can be cut 3 to 4 weeks past this stage with very little loss in dry matter or in feeding value.,4.3 How to make good silage,4.3.1 Harvest at the proper stage of maturity (2)Sorghum should be cut for silage when the seeds are hard. (3)Grass silage forages (grasses, legumes, and cereal crop) should be cut at the same stage at which they would make the best hay.,4.3 How to make good silage,Effect of stage of maturity of forage sorghum silage on its feeding value,From Black et al(1980) Dry matter basis,4.3.3 Cut to proper length The length of the cut section affects the packing and quality of the silage. (2) The proper length of cut varies with the crop and the moisture content. (3) Increase liberation of sugars. (4) Affects voluntary intake. (5) Eliminating most air pockets.,4.3 How to make good silage,Only 20% of particles are longer than 3-4 centimeters,4.3.3 Cut to proper length (6)Chop the silage such that only 20% of particles are longer than 3-4 centimeters. Grass silages should not be more finely chopped than corn or sorghum silage. Wilted and dry forage and forage with hollow stems should be chopped more finely than forage of high-moisture content.,4.3 How to make good silage,4.3.4 Control the moisture content (1) 60%-67% is the best moisture content for most crops to be ensiled. (2) Low moisture silage of 40%-60%moisture is now being preserved successfully in Oxygen-limiting silos. Tall conventional silos that are properly topped-off with heavy , wet forage or sealed with a plastic cover.,4.3 How to make good silage,4.3.4 Control the moisture content (3)Forage containing more than 67%moisture Is heavier and more costly to handle. Is apt to produce slimy, putrid(腐烂的) silage, due to the presence of butyric（丁酸）and other undesired acid. Will have excessive seepage（渗流） of the juices and some loss of nutrients . Will result in excessive deterioration in the silo walls due to the high acidity .,4.3 How to make good silage,(4)With wetter condition, clostridia(梭菌) act on the amino acid normally resulting from proteolysis（蛋白质水解） in the silage to produce amines, ammonia and FA and CO2 Wilting Adding dry hay or straw Adding a dry preservative（防腐剂） Ground grains, corn and cob meal, dried molasses. Combining high and low moisture crops.,4.3 How to make good silage,（5）Method of moisture test Twist method The stems may be twist without breaking The limp（柔软的）leaves should show no signs of dryness. Can not be used for such coarse crops as sweet clover.,4.3 How to make good silage,The grab test( squeeze method),Taking a handful of the cropped forage,Hard squeeze for about 30 seconds,Open the hand slowly, note the condition of the ball of forage in the hand,The oven-drying method,4.3 How to make good silage,Determining forage misture content by the grab test,（6）How to increase the moisture content Cutting shorter and packing more thoroughly. Water can be added. Should be mixed with very green, freshly cut material.,4.3 How to make good silage,4.3.5 An additive or preservative when needed (1) Add nutrients. (2) Provide fermentable carbohydrates. (3) Furnish additional acids to increase acid condition. (4) Inhibit undesirable types of bacteria and molds. (5) Reduce the moisture content of the silage. (6) Reduce the amount of oxygen present. (7) Absorb some acid which might be lost in seepage. (8) Increase N content.,4.3 How to make good silage,Silage additives and preservatives,Feeds additives,Chemical additives,Corn-and-cob meal, Ground corn, barley, oats,Beet pulp（甜菜粕） Chopped corncob or hay,Molasses,Dried whey,Mineral acid（无机酸）, such as phosphoric acid, lower the pH immediately,Organic acid, such as formic acid, propionic acid（丙酸）, etc,Common additives and preservatives (1)Molasses To improve the quality of silage by increasing lactic and acetic acid production. Increase the palatability and nutritive value of the silage. May be added 3.5%-4.0% of the green weight of the forage .,4.3 How to make good silage,Common additives and preservatives (2)Urea 0.5%-1.0% (3) Limestone 0.5%-1.0% ground limestone buffers some of the acids, by continuing the fermatation longer, increases the lactic and acetic acid contents.,4.3 How to make good silage,(4)Organic acids Propionic（丙酸） and formic acid（甲酸） are used for enhancing preservation of forages without the loss of palatability. (5)Sodium metabisulphite（焦亚硫酸钠 ） SO2 is a very antibacterial preservative. It also improves carotene content. (6)Bacterial cultures Acid-forming bacteria like Lactobacillus acidophilus（乳杆菌 ）, Torulopsis sp（球拟酵母 ）, and Bacillus subtilis（枯草芽孢杆菌 ）.,4.3 How to make good silage,Effect of treating corn and wheat silage with formic acid,From Baxter et al(1980),4.4 Use of silage and haylage as a livestock feed,（1）Silage and haylage are used primarily in beef and dairy feeds, as part-or all-of the roughage and also be fed to sheep. （2）Silage is a good appetizer and tends to keep cattle on feed during hot weather or winter.,(3)Once feed withdrawal has begun from a conventional silo, it is best to continue feeding from that silo on an uninterrupted basis until it is empty; otherwise, there will be considerable spoilage of the exposed surface. (4)In the wintertime, a minimum of 1.5 inches of silage should be removed daily from a tower silo; in the summertime, 3 inches.,4.4 Use of silage and haylage as a livestock feed,4.5 Advantages of silage and haylage,(1) It retains a higher proportion of the nutrients of plants than can be accomplished by haymaking. Grass silage preserves 85% or more of the feed of crop, whereas haymaking under the best of condition will preserve only 80%, and under poor condition only 50%-60%. (2)It is a better source of protein and of certain vitamins, especially carotene.,(3) Fewer losses from shattering, leaching（雨水冲洗）, or bleaching（日晒）. (4) Less waste in feeding, even the cobs, shucks（苞皮）, and coarsest stems are eaten. (5) Even weedy crops sometimes make good silage. (6) Less fire hazard than with hay.,4.5 Advantages of silage and haylage,（6）It makes possible the production of the maximum quantity of feed per acre of land and increases the livestock carrying capacity of the farm. （7）It requires less storage space per pound of dry matter than dry hay. （8）It helps to control weeds, which are often spread through hay or fodder. （9）During the monsoon（雨季） months, it becomes exceedingly difficult with dry grasses for making hay.,4.5 Advantages of silage and haylage,（10）It is cheapest form in which a good succulent feed can be provided on most farms. （11）It is a very palatable feed and slightly laxative in nature. （12）It may be completely mechanized as a feeding system, thereby eliminating much labor and time.,4.5 Advantages of silage and haylage,（13）It offers many advantages over pasture, including No fencing required Approximately one-third more forage from the same acreage Harvesting at optimum maturity More uniform quality Little or no bloat,4.5 Advantages of silage and haylage,4.6 Disadvantages of si