high quality silage dairy cattle

Making

HIGH QUALITY SILAGE for

DAIRY CATTLE

By W. B. NEVENS

SEP 1 7 19:~

Circular 686

UNIVERSITY OF ILLINOIS, COLLEGE OF AGRICULTURE

EXTENSION SERVICE IN AGRICULTURE AND HOME ECONOMICS

CONTENTS PAGE

Nine Essential Things to Do .... .. ... ' . 3 What Is Best Kind of Corn for Silage? . . 15

Exclude air, rain, insects, rodents and other animals ... .. ......... 3 dent corn ..... . .. . ............ 15

Select crop with good feeding value .. 5

See that silo is clean and in lower feed value .... ....... .... 16 good repair ...... .... . ... . ... . 5

Cut crop at suitable dry-matter stage 6

Add conditioners if needed . . . . . . . .. 7

Protect silage against freezing ...... 9 Sorghums .... .... . .. .. .. ......... 17

Prevent spoilage at surface by providing a good cover. . . ...... 8

Other Crops Than Corn for Silage ...... 17

Disturb silage as little as possible .. . 10 Sudan grass .. ...... ..... ......... 17

Provide good drainage ..... ... . .. .. 4 Sweet corn is also used ............ 16

Silage Problems ....... .. .... ........ . 12

21

... .. . 22

24

Moldy silage . . ................... 12

Spoilage from overheating .......... 12 Estimating Money Value of Silage . ....

When and how best to add water .. . 13

Ensiling corn stover and Measuring the Capacities of Silos corn fodder ... . . .. .. .. . ... .... 14

Frosted corn .. .. ....... .. ... ...... 14

Hail-damaged corn . ... .. .... .. .. .. 14 of Standing Corn . ............. ...

PAGE

What Illinois tests show about

Corn-cannery refuse has much

High-protein corn is a promising development. .... .......... .... 16

Soybeans ............... ... ...... 19

Cereal grain crops .... .. . . .. ..... . 20

How to Find Dry-Matter Content

Particular attention is given in this circular to the making of corn

silage. The ensiling of grass and legume crops requires such special

care that this subject is treated in a separate publication: Circular

605, Grass and legume SlIages for Dairy Cattle.

Urbana, Ill inois July, 1951

Cooperative Extension Work in Agriculture and Home Economics: University of Illinois , College of Agriculture , and t he United States Department of Agriculture cooperating.

H. P . RUSK , Director. Acts approved by Congress May 8 and June 30 , 1914.

MAKING HIGH-QUALITY SILAGE FOR DAIRY CATTLE

By W. B. NEVENS, Professor of Dairy Cattle Feeding

n IGHTLY MADE and cared for, silage is an economical and ~ highly nutritious feed for dairy cattle, as dairy farmers well know. In the form of silage, the corn crop has about 50 percent more feeding value than when fed as grain and stover. Corn stover standing in shocks in the field loses much of its feeding value, whereas very little deterioration occurs in well-made silage even over a period of many months. Also stock leave much of the dry stover uneaten. Other crops commonly used for silage, including grasses, legumes, and sorghums, have greater feeding value as silage than when fed dry, but the difference is not so great as with corn.

Although silage has been made and used by Illinois farmers for many years, there still are numerous questions about the best crops and varieties to use, precautions that should be taken in making silage, and the causes of partial or complete spoilage of silo contents. The purpose of this publication is to answer some of these questions and to point out the principles to observe in making high-quality silage.

Nine Essential Things to Do

Silage will last for many years, in fact indefinitely, if it is well made and well stored. To keep well and to have good feeding value, it must be made from a suitable crop harvested at the right stage; it must be stored in a well-constructed silo properly prepared for it; and certain precautions must be taken both when putting the crop into the silo and when taking it out.

Excl ude air, rain , insects , rodents and other animals . These must all be kept out of silage if it is to keep well. The best way to do this is to use a well-constructed cylindrical silo. One advantage of the circular silo is that it is more readily reinforced than a rectangular

3

4 Circular No. 686

one, and is not so likely to warp and twist. Any bulging of the wallo is likely to let in air.

The exclusion of air and rain deserve first consideration. Air encourages the growth and development of mold and other microorganisms that cause spoilage and decay. Rains are likely to leach out the silage acids that normally prevent the action of many types of harmful organisms. With the loss of these acids certain bacteria that cause spoilage have their chance, and certain chemical reactions also take place that cause spoilage.

Throughout the more intensive dairy sections of Illinois durable silos of concrete, tile, brick, stone, and wood are common. Whatever the type of silo, it is essential that it be kept in good repair. A roof or suitable covering is needed in order to keep out rain, snow, and birds.

Silos of a temporary nature, such as trench silos and slatted-fence silos, also have a place in emergencies or where building costs need to be kept down. Pea vines are commonly preserved as silage in well-made stacks. The stack method is sometimes used for other crops also.

Chopping the forage fine, mixing the leaf, stalk, and ear portion thoroughly in the silo, and tramping the forage while the silo is being filled will help to free the silage from air. The drier the forag e, the greater the need for fine chopping and close packing.

Provide good drainage. All rain water must be drained away from the silo, especially a trench, pit, semi-pit, or slatted-fence silo. Water that is not quickly drained away from the silage is likely to cause the bottom layer to become soggy and unpalatable. Such silage must usually be discarded.

There may also be too much moisture in the silage itself that must be drained off. When forage crops are harvested for silage too early in their development, that is, when they contain too much moisture, juices may ooze from the silage. If they are put in the silo when they are wet with rain or dew, there will be too much moisture. If there i no way for the excess juice or water to escape, it settles toward the bottom, causing the silage there to become unusually acid (sour) and soggy. A layer several feet deep at the bottom of the silo may be affected. Stock usually will not eat this kind of silage, at least if they can avoid it.

In an upright silo a tile drain should, as a rule, be provided to take off water and juices that collect. The drain should be in the center of the floor, and the floor should slope toward the drain. In trench silos, drainage is sometimes accomplished by excavating the trench on a sidehill and giving the floor a slope downhill to the open.

5 Making High-Quality Silage for Dairy Cattle

If a trench silo is built with a concrete floor, the floor should have enough slope to drain well or a t ile drain should be installed the length of the silo with inlet paced about 15 feet apart.

Select crop with good feeding value. Most forage crops that make good feed in dry form can be preserved satisfactorily as silage. In Illinois, corn is the chief crop so used, although grasses and legumes are rapidly increasing in favor.

When feed is extremely short, weeds and waste product not commonly eaten by stock have proved useful as silage. Stock will eat them more freely in that form than when fed dry, and they do provide some nutrient. However, there is no way to convert these low-grade materials - corn cobs, badly weathered hays, and coarse weeds that are not member of the gra family - into really good silage.

See that silo is clean and in good repair. Before fi lling begins, the silo should be gone over thoroughly, all old silage clinging to the walls brushed down, the floor cleaned, and walls and doors carefully inspected for cracks and other needed repairs.

The doors, if of wood, should be made firm by thorough nailing and replacement of rotted or broken parts. T ack or glue narrow strips of

Corn is the leading silage crop in Illinois. Yields of 10 to 15 tons of green forage per acre are common on productive farms. A much larger proportion of the crop is saved and utilized as feed when it is fed as silage than when cured in shocks in the field and fed as grain and stover.

6 Circular No. 686

felt to all edges that come into contact with the silo walls and with other doors. (Further protection against air entering around doors can be supplied when the silo is being filled. Put over each door a strip of single-ply roofing wide enough to cover the door completely and to extend a few inches on each side. Roll roofing is easiest to handle. Thrust a broomstick through the center of the roll, supporting the stick by a rope fastened to the door frame above the level of filling. Then pull the roll upward, letting the roofing unroll and cover the doors as filling progresses.)

If the silo is a wood-stave one, air may enter through cracks caused by shrinking of the staves. To correct this condition, simply tighten the hoops, brush the walls on the inside with one or more coats of raw linseed oil, and fill the cracks by brushing in melted paraffin.

If the silo is of tile, brick, or cement-stave construction, and has been in use a number of years, shrinking of the mortar joints may have caused fine cracks that let in the air. A simple treatment is to clean the walls thoroughly with a scraper or wire brush and then, using a paint brush, to apply melted paraffin or a coal-tar preparation. When the weather is not too cold, this treatment can be carried out while the silo is being emptied, thus avoiding the trouble and expense of either rigid or swinging scaffolds. A few weeks should be allowed for coal-tar preparations to harden.

Another way of repairing these cracks is to treat the mortar joints with melted paraffin at filling time. Since the paraffin hardens almost immediately, it may be applied to the lower part of the silo before filling starts and to the upper parts during stops in the filling process. With this plan, only a short ladder, instead of scaffolding is required.

Manufacturers of silos are in position to recommend various other suitable treatments.

Cut crop at suitable dry-matter stage. Crops ensiled at early stages of development contain too much moisture for high-quality silage. Not only is the product likely to be sour, soggy, and unappetizing, but there is also likely to be considerable loss of juices from the forage.

Another serious drawback to too-early harvest is the sacrifice in feeding value, the crop not having developed its full yield of nutrients. This objection applies especially to such crops as corn and the sorghums, which normally continue to increase in nutrients per acre until the grain is ripe or until the crop is killed by frost. With pasture and meadow crops, which normally resume growth after each cutting, the stage at which harvesting is done is less important.

Ordinarily corn is best harvested for silage as soon as most of the


kernels are dented and before many of the leaves have dried. While the greatest yield of nutrient per acre is not obtained at this stage, harve t at this time i nece ary in order to get the best keeping conditions and the best feeding value. The denting of the kernels is not alway, however, a suitable harvest guide since seasonal conditions, soil fertility, moisture, and the particular hybrid being grown will all affect this development. If the leaves turn brown before the kernels become well dented, immediate ensiling is usually desirable, for the moi ture content falls rapidly after the leave begin to dry up.

A more accurate way to determine the best time to harvest a corn crop for silage is to make a dry-matter test of the forage . Only simple equipment is needed: a large knife, a scale, such as a kitchen scale or milk scale that weighs to one-tenth pound or to 1 ounce, and a kitchen range equipped with a large oven and an oven regulator. Directions for making thi test are given on page 24.

When the entire forage contains 25 to 30 percent of dry matter, corn is at a uitable stage to be harvested for silage. Less than 25 percent of dry matter means too immature a stage, with the possibility of excess juice and sour silage. When there is more than 30 percent dry matter, the forage may be too dry and the silage may become moldy.

The condition of the leaves is also a good guide to the best time to harvest the corn crop for silage. In most season in tests at Urbana, the leaves of corn at the time the corn was harvested for silage had nearly the same average dry-matter content as the total forage, and the stalks had considerably less dry matter (more moisture), while the ears had considerably more dry matter. These relationships change, however, as the crop matures. When the dry matter of the total forage rises to 35 percent or more, the leaves dry rapidly and may not then be a good index to the condition of the crop as a whole.

When corn come too near the mature stage - that is, becomes too dry - before it is en iled, it may sometimes be a good plan to add water. Thi needs to be done with pecial care, however, as explained on pages 13 and 14.

Add conditioners if needed. Corn and sorghum forages usually contain ample amount of fermentable nutrients, so that conditioners, such as molasses and farm grains, need not be added when these crops are put in the silo. Neither i it necessary to add any other materials if these crops are ensiled at the proper dry-matter stages. When ensiling corn or sorghum forage that has stood in shocks in the field, however, it may be be t to add water, as explained on page 13.

8 Circular No. 686

Conditioners, such as molasses or ground cereal grains, improve the keeping qualities and feeding value of grass and legume silages. Here molasses is being drawn from the drum at the right into the throat of the blower.

The keeping and feeding qualities of grass and legume silages are often improved by the addition of molasses, ground farm grains, or acids (see Circular 605).

Prevent spoilage at surface by providing a good cover. Unless special measures are taken to prevent it, much surface spoilage usually occurs in silos from which silage is not fed for several weeks after the silo is filled . Eight to 10 tons of decayed and moldy silage often have to be discarded from silos opened in spring or summer. Much of this spoilage can be prevented by putting a suitable covering over the silage immediately after the silo is filled .

Strips of a good grade of roll roofing or heavy kraft paper make a satisfactory cover when weighted down with agricultural limestone, clean dry earth, sawdust, or some other material that can be spread well and will not injure the silage.

As soon as the silo is fi lled and before laying the cover, level the cut forage and tramp it thoroughly in order to force out as much air as possible. Then starting at a point opposite the exit, spread strips of the roofing or kraft paper over the forage, lapping the joinings 6 to 8 inches and turning up the ends 6 to 8 inches against the wall. Apply one strip

Making High-Quality Silage for Dairy Cattle 9

at a time, being careful not to step on it. Then on top of the strip pread some of the weighting material, applying not less than 15

pound to the square foot and allowing space along one edge for the overlapping of the next trip. Continue placing strips and weighting them until the entire urface is covered.

Another way to weight down the cover is to pile on it forage from late-maturing or late-planted corn. With this arrangement, the cover i completely laid fir t, then the forage placed on top, just as though the filling operation were being continued. Weeds, wet straw, or other waste materials can also be u ed in this way. Any forage or other moist material placed above the cover will spoil and must be discarded when the silo is opened for feeding.

Covering carefully laid as indicated will be air tight except next to the wall. No poilage will occur below the roofing or paper except in a small area adj oining the wall.

Amounts of roofing and covering material needed. For silos of various sizes these are the minimum amounts of roofing and covering material needed:

Diameter of silo Roofing Covering materials 10 feet. . . . . . . . . . .. 1 roll 1,200 pounds 12 feet ........... . 1% rolls 1,700 pounds 14 feet ............ 2 rolls 2,300 pounds 16 feet ............ 3 rolls 3,000 pounds

Ordinarily the roofing trips must be renewed each year, since they are usually torn when removed.

Coverings for other kinds of silos. Trench, semi-pit, and lattedfence silos can be covered in es entially the same way as a regular silo. For trench and semi-pit silo it is especially important that the covering be above ground level and well rounded so that rain water will drain off rapidly. In a trench silo a layer of earth is commonly placed over the roofing or kraft paper to help pack down the forage, keep out the rain, and retard freezing.

W hen silage is to be used soon. If a silo is to be opened for feeding in a hort time after it is filled, the weighting material can be omitted. Waterproof paper of various kinds, including ordinary wrapping paper that has been treated with lubricating oil, will give satisfactory protection if care i taken to keep the cover pressed close to the wall.

Protect silage against freezing. Freezing does not impair the keeping quality of silage 0 long as the silage is not disturbed. It does, however, make it harder to take silage from the silo and it makes feeding more difficult.

10 Circular No. 686

In upright silos freezing can be prevented by providing a good roof over the silage; by inclosing the removal chutes; by spreading blankets or tarpaulins over the surface and replacing the silo doors each time after silage is removed; in severe weather, by taking out two days' supply of silage at a time and keeping the surface next to the walls several inches lower than the center.

A ring of frozen silage sometimes forms around the walls and clings to them, getting thicker and thicker as cold weather continues. This can be prevented by using a sharp-bladed tool, such as a spade or weed digger, to free any frozen portions from the walls each time silage is taken out for feeding.

Because frozen silage is likely to cause digestive disturbance when eaten by dairy cows, it is best to let it thaw out before feeding it. Usually the easiest way to do this is to let it stand in a feed cart overnight near a stove or in a warm barn.

Disturb silage as little as possible. Silage exposed to the air for 24 hours, especially in warm weather, is likely to spoil. It is best, therefore, when taking it out for feeding to skim a layer of uniform thickness off the top, keeping a smooth, even surface. In hot weather, when molding or fermenting begins within a day or two, it is best to remove a complete layer 3 inches thick every day. In cold weather, well-made silage keeps well in the silo even though none is taken out for several days.

I t is also necessary, when removing silage, to be careful not to stick forks or other instruments into the silage below the layer being removed. To do so permits air to enter and invites spoilage.

The desirability of taking out. a complete layer of silage each day in warm or hot weather is the main reason for building silos of moderate diameter. Unusually broad silos - those more than 18 feet in diameter - have not, as a rule, proved a success because of the large amount of silage that must be removed each day in warm weather, and also because of the amount of hand labor needed to remove the silage.

Silage stored in trench silos is usually taken from one end of the trench. This keeps down the amount of surface exposed to the air. A hay knife or other sharp instrument is used to make a smooth vertical cut from top to bottom. Enough silage is taken out at one time to provide feed for several days.

Tractor-powered scoops are sometimes used to hoist the silage from a trench silo and place it in outdoor feed bunks or load it into feed carts, trailer wagons, or trucks.


Modern machinery has replaced much hand labor in the silo-filling operation. On this farm a field chopper delivered the cut forage into dump trucks. Here the cut forage is being blown into the silo.

A trailer wagon with an apron simplifies the unloading operation on this farm. The apron is moved slowly to the rear by a shaft connected to the power take-off of the tractor at the right. The tractor at the left furnishes power for the blower.

12 Circular No. 686

Silage Problems

Making silage from corn and other suitable crops is fairly simple and usually successful when all conditions are favorable. Often, however, it is not possible to put forage into the silo under the best conditions, and a number of problems arise.

Moldy silage. Molds grow only in the presence of air. When silage is not properly protected, it usually molds and dries out. On the other hand, if it contains too much moisture, it may decay rapidly. Molding and decay normally occur at the surface after the silo is filled, if no suitable cover has been placed over it (see page 8).

Even without a cover, well-made and well-packed silage should have no mold below the surface layer. Moldy silage next to the wall of the silo, with none whatever in the central part of the silage, indicates that the wall is either not air-tight or is so rough that air pockets have resulted from uneven settling of the silage. The remedy for these conditions is to repair the silo or smooth the walls and fill the crack..." as discussed on pages 5 and 6.

When chunks of moldy silage occur here and there throughout the mass of the silage, it is a sign that some air has been trapped in the silage. This means that the forage was either too dry when it was put into the silo or was not packed well enough.

A moldy layer a few inches thick extending horizontally through silage that otherwise is good indicates that the filling process was interrupted at this point. Whenever filling is stopped for 48 hours or more or, in hot weather, for as little as 24 hours, molds start to develop in the surface portions exposed to the air. Unless filling is nearly continuous, - that is, unless it is done daily until the silo is filled,moldy layers are likely to be found.

Forage that has passed the best stage for harvest should be choppeo fine so that it will pack well. Setting the cutter bar for a 74 -inch cut is recommended. When, however, forage is moist enough, there is no special advantage, other than ease of handling, in chopping it fine. Some of the earliest successful trials in making corn silage were carried out by laying bundles of the forage side by side and packing them close in the silo.

Spoilage from overheating . When forage is ensiled under good conditions, fermentation goes on for 10 to 20 days. The temperature of the forage rises above that of the atmosphere and the mass is in a warm, steaming condition. Acids (chiefly lactic, with small amount of acetic) are produced that may make up 1 to 2 percent of the silage,


by weight. As fermenting subsides, the temperature returns to that of the atmosphere, and thereafter the silage will keep indefinitely so long as it is not disturbed or air does not otherwise reach it.

When silage is not well made, an abnormal type of activity by microorganisms may occur, causing a fairly common type of spoilage. Such spoilage is often encountered from day to day as silage is removed for feeding. The silage is warm or hot, and as soon as it is exposed to the air, its temperature tends to rise and it spoils rapidly. As a rule, stock do not relish hot fermenting silage, and if they eat much of it they may suffer from bloat or other digestive disturbances.

Spoilage of this kind may indicate any of the following conditions:

1. Small amounts of air are constantly seeping into the silage. Perhaps the silage was not well packed, or it was put in stacks that have slipped, or it was stored in a temporary silo, such as a slattedfence structure, where it has gradually settled unevenly.

2. The forag e was too dry when it was put into the silo. In forage that is too dry, fermentation may continue for too long a time.

3. The amount of fermentable nutrients in the silage was too low. Most crops other than corn and the sorghums, make better silage when conditioner are added, as explained on page 8. Particularly in legume silages, overheating may be traced back to lack of sufficient amounts of fermentable nutrients in the forage.

When and how best to add water. Forage that contains the right amount of moisture when it is put into the silo makes better silage, as a rule, than forage to which water must be added. Nevertheless, by doing a good job of mixing the water and the forage, the keeping quality of silage that was somewhat too dry when it went into the silo can be improved by the addition of some water.

Corn forage that contains ears with hard kernels and thoroughly dry husks is usually too dry to keep well as silage. The drier the corn, the harder it is to cut the husks and stalks fine enough for close packing and the more difficult it is to pack the silage close enough even if it has been chopped fine. Water helps to soften the dry portions so that they can be packed more closely, thus excluding air. At the same time water furnishes added weight, which also helps to pack the silage down.

When water under pressure is available, it is ordinarily best added by being allowed to flow into the flexible distributor pipe of the silo filler or blower. Or one of the men tramping the silage can carry a hose and wet the silage during the tramping. Wetting can be continued

14 Circular No. 686

between unloadings if care is taken to see that the water is well distributed over the entire surface.

If the water is not under pressure, it may be introduced into the blower fan case or into the blower pipe just above the blower. Either way, the water should be shut off each time before the blower is stopped.

Adding water after the silo has been filled is not satisfactory because it tends to seep down along the wall and does not permeate the forage sufficiently. Also any large amount of water added after the filling is done may leach the nutrients from the silage.

When corn or other forage is very dry, a large amount of water i required. The amount added from an ordinary %-inch garden hose during the few minutes required to blower-elevate a load of chopped forage into the silo is usually not enough. Moreover, time should be allowed for the water to soak into the forage. A more effective way to add water is to soak the load of chopped forage with water before and during unloading and then add more water in the usual way while filling the silo. However, the addition of so much water as to cause seepage from the silo should be avoided.

Ensiling corn stover and corn fodder. Occasionally corn stover or corn fodder which has been cured in shocks in the field is ensiled. Since these forages are very dry, more water is required than when a freshly harvested crop is being put into the silo, and greater care in packing the forage is needed. Chopping the forage fine and, if ears are included, distributing the leaves, stalks, and grain evenly throughout the silo are essential. Tramping while water is being added will help to moisten all portions of the cut forage and to pack it well. Further suggestions on when and how best to add water are given in the preceding paragraphs.

If a trench silo is being filled, driving over the forage in the trench with a tractor or truck will help to pack it.

Frosted corn. Corn that has been killed by frost may yet make good silage if it is put into the silo immediately and if the precautions for good silo filling already outlined are followed. There are two reasons why immediate action is necessary: Much of the feeding value is in the leaves, which begin to dry up within a few days after the corn is killed, and may blow away. Also dried forage is harder to keep.

Hail-damaged corn . If corn in the milk stage or earlier in its development is stripped of its leaves, it usually fails to mature a crop of grain. Ears in the milk stage that remain on such stripped plants may begin to mold within a few days. Often the plants die within a


week or two. For these reasons, if plants that have reached the ear stage are so damaged by hail as to be stripped of their leaves, the crop should be ensiled at once.

What Is Best Kind of Corn for Silage?

This is one of the most frequently asked questions on silagemaking. The answer is, briefly, that for silage purposes on dairy farms a h igh-yielding dent hybrid that ordinarily reaches maturity before frost is superior to other kinds of corn.

What Illinois tests show about dent corn . The above conclusion is supported by extensive trials carried out at the Illinois Station. In these trials it was true that the large-growing late-maturing sorts of corn produced more tons of green forage per acre than did those kinds that matured the grain earlier; but the kinds that matured the grain had, in most seasons, a higher proportion of the crop in the grainhence a higher yield of dry matter per acre, which means a higher yield of nutrients and greater feeding value.

In "late" seasons, that is, in seasons unfavorable for maturing the grain, the late-maturing sorts of corn had another disadvantage: because the grain reached only the milk stage before frost, the forage had a still lower proportion of dry matter than usual, hence still lower feeding value. Silage from this kind of immature corn is also likely to be too acid, and cattle will not eat it so readily as silage made from well-matured corn.

The figures in Table 1, showing the yield of dry matter in the forage of hybrid dent corn in five different seasons, is of interest at

Table 1. - Yields of Corn F orage Harvested for Silage, and P roportion Each Part of P lant Contributed to Total Cropa

Year Yield of dry matter per

acre of forage Yield of ears per

Proportion of dry matter of crop in-

Ears Stalks Leaves Total acreb Ears Stalks Leaves

tons tons tons tons bu. perct. perct. perct.

1942 ...... .93 .88 .67 2.47 31 37.6 35.4 27.0 1943 ...... 2.53 1.25 1.07 4.85 85 52.2 25.7 22.1 1944...... 1.64 1.36 1.08 4.09 55 40.2 33.4 26.4 1945 ...... 1.50 1.52 1.07 4 .08 50 36.8 37.1 26.1 1946 . ... .. 1. 98 1.57 1.15 4.69 67 41. 7 33.9 24 .3

a Compiled from data reported in Bulletin 533 of this Station. b In terms of ears containing 15 percent moisture, 70 pounds of ears to the

bushel.

16 Circular No. 686

this point. In 1943, when the corn went into the silo at a well-advancedstage of development, the ears made up more than 50 percent of thedry matter in the forage. In other seasons, when the corn washarvested at a less advanced stage, the ears formed only about 37 to42 percent of the dry matter. 1946 was one of these years. While thetotal yield of dry matter in the 1946 crop was but slightly less thanin 1943, the yield of ears was about half a ton, 18 bushels, less.

Hybrid corn that matures the grain before frost has another advantage as a silage crop - any acres remaining after the silo or siloshave been filled can be harvested for grain.

Sweet corn is also used. Sweet corn may be used for silage in thesame way as dent corn. While the forage yield is usually less fromsweet corn than from dent corn, some of the larger-growing sorts ofsweet corn do yield well.

Sweet corn harvested when the grain is in the milk stage is likelyto produce a sour silage if the ears are included in the silage. Theforage left after the ears are harvested for canning has, of course, amuch lower feeding value than the forage of dent corn grown forgrain and containing the ears.

Corn-cannery refuse has much lower feed value. Silage madefrom cannery refuse, consisting of husks, cobs, and overripe anddamaged ears of sweet corn, is worth only about 60 to 75 percent asmuch as silage from well-matured dent (or field) corn. In experimentsat this Station the proportion of the dry matter which proved to bedigestible was about the same as in normal corn silage. But the feedingvalue of the silage, as indicated by both dry-matter content andquality of nutrients, was equal only to about that of silage from latematuring field corn.

Silage made from cannery refuse may have such a high acid content as to make it unpalatable to some animals.

High-protein corn is a promising development. Hybrids especiallyselected for their high protein content are receiving considerable attention as silage crops, as they offer the possibility of good yields offorage with 50 to 100 percent more protein than unselected corn. Whenhigh-producing dairy cows are fed high-protein corn silage, they donot need so much high-protein concentrates.

However, for high-protein corn actually to produce forage with ahigher protein content than that of other corn, the soil must be wellsupplied with available plant nutrients. Side-dressing the corn withnitrogen fertilizer at the same time as the last cultivation is one way


to get this higher-than-normal protein content. Harvesting the crop early is another way of getting it; but a already pointed out, a tooearly harvest usually means a sacrifice in yield.

Other Crops Than Corn for Silage

Although in Illinois silage made from field corn has the best feeding value, soil conservation or emergency situations - insect infestations or failure of the corn crop - may make it advisable to grow other crops. Some suggestions for growing emergency crops adapted to Illinois conditions are given below. The making of silage from these and other grasses and legumes is discussed in a separate publication, Circular 605, Grass and Legume Silages for Dairy Cattle, which will be sent on request.

Sorghums. The sorghums are similar to corn in their adaptability for silage purpo es. They may be harvested and ensiled in the same way as corn. The weet sorghum , or sorgos, are preferred.

A number of the sorghums do not mature in central and northern Illinois, and ilage made from them is likely to have more water and acid than normal corn silage. Though sorghum silage is therefore likely to keep well, the feeding value is usually less than that of corn silage. Cattle sometimes refuse silage that is very acid.

Good-quality ilage may be made, however, from early-maturing sorghum, such a Early Sumac, Rox Orange, Early Amber, Norkan, and Blackhull kafir, or by growing mixtures of corn and sorghums, or by mixing the sorghum forage with soybean or corn forage at the time of en iling.

The late-maturing varieties of sorghum, such as Atlas and Kansas Orange, often give higher yields of forage than does corn. Early maturing sorghum may yield no more or slightly less than corn. Dwarf or combine types of sorghum are not recommended for use as silage. (For further information on varieties, culture, and use of sorghums for forage, see Farmers' Bulletin 1944, U. S. Department of Agriculture.)

Sudan grass. This is an excellent crop for emergency use for either pasture or ilage. Yields of Sudan grass and Sudan-grass mixtures at Urbana have ranged from 5 to 13 tons of green forage to the acre. A forage harvester simplifies the handling of this crop.

The sweet variety of Sudan resists disease better and remains green longer than the common variety. It may be ensiled without a condi

18 Circular No. 686

tioner, whereas with the common variety it is advisable to use molasses (40 to 50 pounds per ton) or some other conditioner.

Seeding 1 Y2 bushels of soybeans with the usual amount of Sudan seed will increase the yield and improve the feeding value of the crop. Soybeans are resistant to chinch bugs and can usually be depended on to provide a good crop even when the Sudan is killed by the bugs.

In Illinois, early-maturing sorghums, such as Early Sumac and Rox Orange, make a better silage than do large-growing, late-maturing varieties, such as Kansas Orange shown above at the right.


The sorghums yield tonnages of green forage comparable with corn. The late-maturing sorts produce heavy yields but the quality and feeding value of the silage is usually less than that of corn silage.

Soybeans. Silage of good keeping and feeding quality may be made from soybean forage. Best results are obtained when molasses (100 pounds per ton) i added or when the soybean forage is mixed with sweet Sudan or sorghum forage. The beans may be grown in rows or drilled solid and harve ted with a forage harvester.

Soybeans may be used for silage if they are harvested while the leaves are still green. Large-growing varieties, such as those pictured here, are recommended.

20 Circular No. 686

Sudan grass is a good emer gency silage crop. It can be sown somewhat later than corn but as a rule gives lower yields. Seeding soybeans with Sudan will increase the yield of forage and improve its feeding value.

The larger-growing varieties of soybeans, such as Chief, Gibson, and Virginia, produce large amounts of forage. The yields of forage from soybeans at Urbana have been about half as large (in tons) as from corn.

Cereal grain crops. In emergencies, silage may be made from cereal grain crops - barley, oats, rye, and wheat - but the quality is not as good as when legumes or pasture and meadow grasses are used. Even when molasses is added, silage made from the forage of a cereal grain tends to remain hot and to spoil quickly on exposure to air.


Estimating Money Value of Silage

In computing feed costs and in settling accounts between landlords and tenants, a method of estimating the money value of silage is needed.

Corn silage. A convenient and fair method to use to compute the value of corn silage is to apply to the corn grain the market price of corn, and figure the stalk and leaf portions as having the same value a an equivalent amount of other roughage. It is fair to figure that a t on of corn silage produced under central Illinois conditions in an average y ear will contain 4 bushels of corn grain, and that the stalks and leaves will have the same feeding value as 340 pounds of grass hay . Simple multiplication does the rest.

The above amounts of grain and forage are based on tests at Urbana reported in Table 2. In these trial a ton of the corn silage averaged 4 bu hels of ears and 375 pounds of stalks and leaves, but

Table 2. - Yields of Corn Forage Harvested for Silage and Amounts of Ears, Stalks, and Leaves per Ton of Foragea

Forage Ears Stalks andNumber leaves perYear of hybrids Total Dry-matter Per Per ton ton ofin test yield content acrea offorageb foragee

tons perct. bu. bu. lb. 1940 ... . .... ... 10 13 .2 32.8 70 5.3 400 1941 .. . ........ 8 13 .3 29 .0 50 3 .7 420 1942 . ... ....... 12 9 .5 26.0 31 3.3 380 1943 . . . . . . . . ... 12 16 .0 30.3 85 5 .3 340

1944 .. . ........ 12 16.4 24.9 55 3.4 350 1945 . .. . . ... ... 12 16 .0 25.5 50 3.1 380 1946 . .. ... .... . 12 17.4 26.9 67 3 .8 370

Average . . .. . . ....... . . . 14 .5 28.0 58 4.0 375

a Compiled from data reported in Bulletins 494 and 533 of this Station. b In terms of ears containing 15 percent moisture, 70 pounds of ears to the bushel. e In terms of forage containing 15 percent moisture.

since the stalks and leaves have only about 90 percent as much feed value as good-quality grass hay, this average figure has to be reduced to 340 pounds before applying to it the farm price of grass hay.

Other silage. Silage made from other crops than corn may be esti mated as worth 25 to 30 percent as much as a ton of the same crop

22 Circular No. 686

when well cured and in equally good condition, for it takes 3% to 4 tons of green crop as it stands in the field to make one ton of wellcured hay or other forage.

A more exact method of arriving at the value of a given lot of grass or legume silage is to take a sample and dry it, weighing it before and after drying. For example, take a sample of alfalfa silage. Weigh it and spread it in a pan placed in a warm room where the air will dry it naturally. Stir frequently to prevent spoilage. Let it dry until it will lose no more weight. Then weigh it again.

Suppose the sample as taken from the silo weighed 4.5 pounds, and after drying, 1.3 pounds. Then 1.3 --;- 4.5 X 100 = 28.8, the percentage of air-dry matter in the silage. The feeding value of the silage, therefore, is about 29 percent as much as that of alfalfa hay. If the hay i valued at $14 a ton, the value of a ton of the silage is $14 X 0.29, or $4.06.

Measuring the Capacities of Silos

Because of wide differences from year to year in the moisture content of the crop ensiled, it is impossible to state exactly the capacity of a silo in terms of tons. For example, a silo holds many more tons of corn harvested at an immature stage (when it is

Table 3. - Capacities of Silos : Approximatea

(These figures are for settled silage. Note that as depth increases, capacity increases more than proportionally, due to the fact that the greater weight packs the silage more tightly.)

Amount of silage at given silo diameterb Depth of silage

10 feet 12 feet 14 feet 16 feet 18 feet 20 feet

tons tons tons tons tons tons 20 feet . . . .. . ....... . .. . 35 50 68 89 113 139 24 feet .... . . . . .. ~ ... . . . 43 62 85 111 140 173 28 feet ... .. . . ... . ' .. .. .. 52 74 101 132 167 207 32 feet . . ... ...... . . . .. . 60 87 118 154 195 241 36 feet . ... . ....... . ... . 135 176 223 275 40 feet ... . ....... . .. . . . 152 198 251 310 44 feet . . . ... . ... .. . . . .. 220 279 344 48 feet . .... .. . . ...... .. 307 379

a The information given above is taken from Circular 603, U. S. Department of Agriculture.

b Based on well-eared corn silage cut in ¥.!-inch lengths or less; harvested before kernels are fully dented and hard, with about 70 to 74 percent moisture. Quantities will be less for longer cut, fewer ears, or lower moisture content.

Making High - Quality Silage for Dairy Cattle 23

high in water content) than it does of fully mature corn . The same principle applies to other crops. Also, a crop that has been wilted before it is put in the silo weighs less per cubic foot than the same crop ensiled directly after mowing.

With the above points in mind, an approximate estimate of the capacity of a silo for any kind of silage can be made from Table 3.

Measuring contents of a partly emptied silo. Table 3 can also be used to calculate the approximate weight of the silage remaining in a partly emptied silo. Fir t find the approximate weight of th,e silage put into the silo. Then find the capacity of a silo the size of the part which has been emptied, and subtract this from the first figure. The difference i an approximation of the amount of silage remaining in the silo. For example, the settled silage in a silo 14 by 44 feet was originally 36 feet deep. Twelve feet of silage remains in the silo. The table shows that 135 tons of silage were put into the silo. The part emptied is equivalent to a silo 14 by 24 feet, which has a capacity of 85 ton . The difference between 135 and 85 is 50 tons, the amount of silage remaining.

Since silage packs more heavily into the lower part of a silo than into the upper part, it i clear why we cannot figure the tons left as proportional to the number of feet left.

Weight of silage per cubic foot. Freque:qtly questions are raised concerning the weight of corn silage per cubic foot. Table 4 gives this information for silage stored in cylindrical silos to a depth of 35 feet. At depth greater than 30 feet the weight per cubic foot continues to increase, though only slowly.

Table 4. - Average Weight of Settled Corn Silage per Cubic Foot"

Average weight per cubic foot

Depth of settled silage At depth For all silage above indicated depth indicated

pounds pounds 15 feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 50 . 5 41.8 20 feet .. . . . .. .. . . . . . . . . . . .. . . . .. . . . . . . . . . . . . .. 52 .4 44.3 25 feet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. 53.7 46. 1 30 feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54.4 47.4 35 feet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54 .8 48.5

a From Circular 603, U. S. Department of Agriculture.

24 Circular No. 686

How to Find Dry-Matter Content of Standing Corn The dry-matter content of standing corn can be deter

mined by taking a sample and drying it, according to the following directions. In order to minimize evaporation, the sampleshould be cut and weighed rapidly and in a shady place.

1. If the whole plant is to be used as a sample, harvest 6 to 8 representative plants with a corn knife. Split the stalks lengthwise and cutthe plants into pieces not more than 1 to 1% inches long. If leaves andhusks are to be used as a sample, strip all of them from 5 or morerepresentative plants. Cut these leaves and husks into pieces 1 to2 inches long. Do not include tassels, stalks, or ears.

2. Mix thoroughly and take a sample weighing not more than 4 to5 pounds. Weigh to 7io pound on a milk scale or a kitchen scale.Record this weight.

3. Line shallow baking pans with newspaper and spread the samplecorn in them. Place in an oven and subject to a temperature that willdry the corn rapidly without charring the paper. For the first hour,keep the temperature at 250° F. After the first hour keep the temperature at 225 °. For samples comprising the whole plant, overnight drying may be needed. For samples consisting of leaves and husks only,three or four hours of heating is usually enough. However, continue todry the sample until it ceases to lose weight.

4. In order to find the percentage of dry matter, divide the weightof the sample after it has been completely dried by its weight justafter it was cut. If a sample weighed 4.2 pounds just after it was cutand 1.3 pounds after it was dried, the percentage of dry matter wouldbe 31 (1.3 -;- 4.2 X 100).

The dry-matter content of crops other than corn and also of silagecan be determined in a manner similar to that described for corn.

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