LIFE & HEALTH THOMAS A. REEVE GAYLAND D. ROBISON HAROLD R. GUENTHNER Cooperative Extension Service Max C. Fleischmann Coil. of Agriculture University of Nevada Reno HARVESTING AND STORAGE OF SORGHLIM Sl LAGE Thomas A. Reeve, Gayland D. Robison and Harold R. ~uenthnerl' SUMMARY Forage sorghum silage can be a high quality feed with proper harvesting. There is no substitute for good manage-ment. The control of factors such as harvesting at the proper stage of maturity, moisture content, fineness of chop, distribution and packing for exclusion of oxygen and sealing the silo is essential. Good equipment and management are the keys to preserving sorghum si lage quality. The farmer needs to use his judgment in considering whether an additive should be used. Preservatives and additives will not substitute for proper exclusion of air, nor produce additional nutrients in the silage, and usually the cost in terms of silage value is too high. Losses occur with spoilage and there are no "all-in-one" addi-tives. Why raise a quality feed only to lose it by improper harvesting and storage procedures? INTRODUCTION Forage sorghums are summer annuals that can tolerate 'ought and heat typical of the southwestern United tates. Also, they respond well to supplemental moisture. rhey are adapted to Southern Nevada climate and produce a large quantity of high quality feed for dairy and cattle operat ions. Production and growth of sorghum is limited to the summer months. This makes it necessary to preserve the feed for use over a longer period. Ensiling provldes such a means of preservation and allows better feed distribu-t ion. Sorghum silage, if handled properly during ensiling, will preserve most of the original value and provides a moist palatable feed that w i l l serve as a major source of nutrients and bulk in the ration. The quality of silage produced is no better than the material placed in the 1' Jr. Agronomist and Assoc. Agronomist, respectively, Southern Nevada Field Laboratory, Logandale, Nevada and Extenslon Agronomist, University of Nevada Reno. silo, but nutritional value and quantity can be lost with improper hand ling. HARVESTING Harvesting is important in determining the quality of silage produced. Good quality silage can be produced from forages with proper control of certain factors, such as: 1. Maturity at harvest, 2. Length and unlformity of cut. 3. Proper moisture content when ensiling. Maturity: The stage of maturity is an important factor to consider before harvesting sorghum for silage. Since a high percentage of the nutrients are in the stalk, silage sorghum should be harvested prior to maturity. This is also important because of the digestibility of the grain. If sorghum is matured past the dough stage of develop-ment, a higher percentage of undigested grain will pass through the animals than if harvested at soft dough stage. Thus some of the nutritional value is lost. There are several essential processes in the plant associated with grain development that aid in determining maximum ensilage. Sugar content re'aches maximum about the milk stage of development then declines slightly as it matures. Dry matter increases and acidity decreases (lower pH) as plants mature. Total nitrogen and minerals decrease wlth advanced plant development. Sugar, nitro-gen and minerals are a measure of silage's nutritional value. Dry matter content and silage acidlty influence preservation. High molsture content results In excessive seepage and loss of nutrients and tonnage. Low moisture content, however, prevents adequate packing and in-creases spoilage. A silage pH of about 4.5 allows for better preservation and a more palatable feed. Higher pH levels favor formation of butyric acid and spoilage of sllage. Length and Uniformity of Cut: Uniformly fine chopped pieces have several advantages over large-cut pleces. Improved silage develops since the forage is better ex-posed to bacterial action whlch causes fermentat ion. Coarse-shredded sorghum Is dlff icult to pack or exclude air and increased spol lage results. Molsture Content: As a rule, sorghum silage should be harvested when the grain is at the soft dough stage with a molsture content of 65-70 percent. Lower moisture forage may be difficult to pack properly in order to ex-clude air, and spoilage results. Nutrient losses from spoilage occur at high moisture percentages. Therefore, moisture content of 65-70 percent at the soft dough stage is a good tlme for harvest. When the moisture content of the forage Is less than 65 percent, water should be added during the ensiling. PROCESS OF Sl LAGE FORMATION Plants "breath" as they live. This means they respire by using oxygen and giving off carbon dloxide. When green forage is placed In a silo, it continues respiring until all the trapped oxygen is depleted. Wlthout oxygen, molds will not grow. Within a few hours, bacteria begins to increase in large numbers. These are acid formlng bacteria and act on sugars and carbohydrates to form lactic acids. Heat is generated by the process which favors lactic acid productlon. The process continues until the pH drops from about 5.5 to 4.0. After a certaln level acid is produced, fermentation is stopped and the forage is preserved. Losses of 5-10 percent always occur durlng fermentation. Bacteria necessary for fermentation are present on the forage in large numbers. ENSILAGE STORAGE Several factors must be considered in the proper en-sl llng of a forage. They are: 1. Type of storage. 2. Loca-tion of storage. 3. Filllng the silo. 4. Packing. 5. Sealing or covering. Losses on a poorly fliled, packed or un-sealed silo can reach 50-60 percent or even more. Types of Silos: Several types of structures are used for storage of sl lage. They range from elaborate upright sealed silos, to open above ground storage plles. The type of s1 lo constructed depends on individual needs, the desired premanency, mainly dealing wlth methods of f i I I i ng and removl ng silage. However, regard less of shape, size, construction, filling methods, etc. the functlon of a silo Is to preserve forage for feedlng at a later date. Silos must have hard surface floors and airtight walls for satisfactory results. The exclusion of air pockets and preventing alr exchange from the surface is Important In reduclng spoilage losses. If bunker, trench or pit sl 10s are used, the side walls should slope outward at about a foot per ten feet of rise. 'This allows for better packing and air exclusion. Location: A silo should be located where i t is acces-sible for filling and removal. The site should be located in a welldrained area where seepage, flood waters or rainfall will drain away. The silo should also be located where prevailing winds will not carry odors to the farm-stead or residential areas. Location of the si lo may also influence the type built. Packing: Thorough packing of the forage increases the silo's storage capacity, crushes and lacerates the ma-terial, reduces the subsequent settling, and excludes air that promotes spoi lage. A wheel tractor with a blade will move and pack silage adequately and is recommended over a crawler tractor. A crawler tractor and dozer blade can be used for packing, but in most instances the silage is not as uniformly packed due to piling up and the lower weight per square inch of contact between equipment and silage. Forage should be dumped and packed with as little motion as possible to avoid contamination with foreign material. The surface of the silage should be kept smooth and the ends steep but we1 l packed. Sealing or Covering: Purpose of sealing the silo with a cover is to exclude air and water from the exposed surface. Several types of materials can be used as co-verings. The material selected should not be too expen-sive and s t i l l seal the silo properly. The silage surface should be covered as soon as possible to reduce spoilage due to exposure of air. Covering silage after six hours is recommended because of harvesting and f i l ling proce-dures. It is advisable to cover and seal properly after each day's filling. Polyethylene covers can be used successfully in reducing spoilage losses. Polyethylene film should be weighted down with materials such as sawdust, boards, soil or tires to prevent air movement beneath the plastic. This material is easy to install and can be used again if care is taken not to tear or punch holes in it. Other materials, such as sawdust, paper, straw, etc. have been used but do not exclude all air or rainfall. Spoilage is usually high with these coverings. Sealing material costs shou Id not exceed the value of silage saved by the seallng. SILAGE ADDITIVES In deciding the need for additives, one should consider the factors for producing good silage. They include oxy-gen, moisture, bacteria and the chemical composition of !he forage material. These factors are all satisfactory when good forage is properly ensiled. The benefit of additives is measured only by the reduction in losses and/or in improved quality. Additives will not replace good management. Dry Matter: If forage is too high in moisture content at harvest, the addition of dry matter w i l l help absorb moisture and reduce seepage losses. Grain can be used. Urea: Urea is added to improve protein content. How-ever, more benefit is derived from using i t as a supple-ment rather than as an additive. Grain: Grain is often added to reduce moisture and improve nutritional value, but losses can occur with spoilage and the grain may be more beneficial as a supplement. Molasses: Molasses is added as a sugar source, but additional sugar is not needed for corn or sorghum si lage. Losses can occur from spoilage and seepage. Others: There are many other types of additives but they have riot proven effective. NUTRITIONAL SUPPLEMENT Storage losses from 10-12 percent are possible from properly sealed, airtight silos and there is always a 5-10 I percent loss from fermentation. Addltives to improve nutritional value of the silage therefore, should be inex- I pensive to be profitable because much of their nutritive value could be lost through spoilage or seepage. We usually advise feeding protein concentrates as a supplement rather than risk losing this In storage. By following good management practices and hand llng the forage properly, good palatable feed is produced without additives. Cooperative E xtension work In a g r i o u l t u re and home eoonornlos, Slate of Nevada. The Unlverslty of Nevada College of Agrioulture and the U.S. Department ol Agrlaul-lure cooperating. Dlalrlbuted In furtherance of purposes pwlded for by Acts of Congress of k8y 8 and June 30, 1914. DALE W. BOHMONT, Director J. F. STEIN, Associate Dlrecta.