Well-eared corn silage has been extensively used in beef cattle feeding for many years. Of all feed crops, it is generally the top producer of nutrients per acre. Thus, a liberal use of corn silage allows the farmer-feeder to market more pounds of beef from his farm than from any other procedure. It makes efficient use of the corn stalks, leaves and cobs which are usually wasted when only the grain is fed.
With its solid stems, high carbohydrate content and generally desirable moisture level, corn can be ensiled with few problems. The primary requirement is that the fermentation take place in the absence of oxygen. This can be accomplished in many types of upright silos, bunker silos and even in stacks covered with plastic when made in large volume. The corn plant should be finely chopped to pack well in the silo. When made in stacks, it is difficult to avoid surface spoilage. They should be used only for large amounts when the weight of the chopped corn is great enough to aid with the packing and the surface area is a relative small percentage of the total. It is also difficult to feed from a stack without undue spoilage. They can best be used to refill upright silos when a large amount is moved at one time.
Energy is the nutrient required in greatest amounts by finishing cattle. Well-eared corn silage is approximately one half corn grain on a dry matter basis. Corn which will produce the maximum yield of grain per acre should be used for silage production. Practices which increase vegetative growth but interfere with ear development reduce the amount of feed per acre. Such practices include: planting long season hybrids which are harvested before maturity; planting too thick or mixing with other crops.
The most rapid storage of nutrients in the corn plant occurs when the kernels are filling. If harvested for silage when immature, the yield will not only be reduced but the silage will be less palatable. Research has shown that silage made from well dented corn has a higher feeding value than that from immature corn. Such corn will have nearly all of the husks dry as well as the lower leaves and will contain about 35 percent dry matter.
Silage yields, silo capacities and silage consumption data are generally expressed in total weight, such as tons per acre or pounds eaten per head daily. Such figures are rather meaningless unless some idea of the dry matter content of the silage is known. For example, the difference between a 25% and a 35% dry matter silage may not seem large but the 35% really contains 40% more dry feed than the 25%. Even between 30 and 35% dry matter silages, the drier silage contains 17% more actual dry feed.
On the other hand, weight of dry matter per unit of volume varies relatively little. This is, wagon loads of chopped corn or silos full of silage will contain about the same weights of dry feed even though their total weights may vary widely due to differences in the amount of water contained. For example: a silo 20 feet in diameter containing 54 feet of settled silage would contain approximately 129 tons of dry matter. This amount of dry matter would represent 258 tons of 50% dry matter material, 387 tons of 33-1 / 3% dry matter material or 516 tons of 25% dry matter material.
Since no special problems were encountered during ensiling and a highly nutritious feed was produced, no research on the preservation of corn silage was conducted for many years. Many experiments verified the value of silage but little had been done to explain the high value or determine how it might be further improved.
Cattle and lamb feeding trials have shown the organic acids present in silage to have a high feeding value. This was especially true of lactic acid, the major one found in corn silage. If the amount of lactic acid in corn silage could be increased, would the silage have a higher feeding value?
Fermentation in the silo continues until a certain amount of acid is produced, the amount being directly related to the moisture content of the ensiled material. When this degree of acidity is reached, fermentation stops and the silage is preserved as long as air is kept from it.
Since the acids produced eventually stop the fermentation, it was found through research that the addition of ground limestone would neutralize these acids. This makes fermentation last longer with more total acids being produced. The addition of one percent (20 lbs. per ton) of pulverized limestone approximately doubles the lactic acid content of the resultant silage.
A number of experiments were conducted to determine if this increase in lactic acid content would increase the feeding value of the silage. The results showed that the addition of one percent limestone to chopped corn at time of ensiling reduced the amount of silage required per pound of gain. This increase in feed efficiency averaged 6.5 percent. Although this is not a large increase, limestone is low in cost and its use offers other advantages.
The addition of limestone corrects the normal calcium deficiency of corn silage and the treatment reduces the amount of molding and spoilage which may occur in the feed bunk in warm weather. Another effect of the acid neutralization is that acids are less likely to attack silage walls. The increased fermentation would also tend to increase the breakdown of nitrates should they be present in the ensiled material.
In the experiments discussed above, which were conducted at the Ohio Agricultural Research and Development Center, the ground limestone was added by sprinkling over the top of the loaded wagons of chopped corn. This is a tiring and time consuming procedure, hence, a metering device at the blower which can be filled from the ground is more efficient.
Limestone or a mixture of equal parts limestone and urea were found to be of equal value in producing organic acids in silage. For this purpose, limestone is much cheaper but urea supplies nitrogen, a source of crude protein which is deficient in corn silage for growing-finishing cattle. When corn silage is full fed with little or no grain, 10 lbs. of urea per ton will meet the protein requirement. When corn grain is fed at one percent of body weight per day (about half feed) with corn silage, 20 lbs. of urea are needed per ton. In three experiments conducted at the Ohio Agricultural Research and Development Center, 20 lbs. urea, 10 lbs. of limestone, and 2 lbs. of defluorinated phosphate were added per ton of silage which was fed with a half feed of dry shelled corn. Thus ration was not improved by adding supplemental natural protein from dehydrated alfalfa meal, soybean meal or a mixed protein supplement, all of which increased the cost of the ration at that time.
Non-protein nitrogen may also be added to corn silage by the use of anhydrous ammonia. Pro-Sil is a proprietary mixture of molasses, anhydrous ammonia and minerals. These materials are handled as a liquid and hence can be pumped.
Recent, marked increases in the cost of all forms of nonprotein nitrogen have removed much of the advantage of adding these materials to corn silage. Relative costs should be checked with other sources of protein in deciding how to correct the protein deficiency of corn silage.
Numerous other additives for corn silage are being marketed. These include fermentation solubles, antibiotics, enzymes, various mixtures, unspecified materials, etc. Some of these have been shown to be of benefit when added to hay crop silage. Unfortunately, sufficient controlled research is not available to evaluate them as additives to corn silage.
Although well-eared, well-matured corn silage is the top producer of beef per acre, it does not contain sufficient energy to fatten young cattle at light weights. Levels of feeding and types of cattle will be discussed later. However, one rule-of-thumb often used is to feed one pound of grain per hundred pounds of body weight per day, plus all of the corn silage the cattle will eat.
In order to simplify storage and feeding, attempts have been made to produce a complete energy feed that could be stored in a single silo. Investigators at the Michigan Station were successful in producing such a feed by the use of "center-cut" silage. This silage was harvested by cutting higher than normal and by removing the top of the corn plant above the ear. Thus, a silage-containing a higher than normal percentage of grain and hence energy can be produced.
Experiments were conducted at the Ohio Agricultural Research and Development Center to fully utilize the corn plant by feeding growing-finishing cattle and a beef cow breeding herd. Ear corn was picked, processed through a combination chopper and roller mill and added to chopped whole plant corn from a similar area, thus, producing "Double-ear" silage for finishing cattle. The stover remaining after the ears were picked was chopped and ensiled for cow feed. Ten pounds of urea, 10 lbs. of ground limestone and 2 lbs. of dicalcium phosphate per ton were added to both silages. These silages were produced in two consecutive years and fed to growing-finishing calves and mature Hereford cows, respectively, as their only rations. Results with both silages were very satisfactory.
Other methods of stepping up the energy content of corn silage have been investigated. However, none of them have been adopted on a wide scale. Most of them require either extra machinery, specialized equipment or additional labor at time of harvest. For these reasons, most producers harvest and store corn silage and corn grain separately by conventional means and combine them in desired amounts at feeding time. This simplifies harvesting procedures and allows more flexibility in varying silage to grain ratios at feeding time.
Research is continuing on how best to salvage, for beef cow feed, corn crop residue following harvest with a pickersheller. Numerous methods and machines are being used to salvage a part or all of the residue as silage or dry feed. Although there are problems in keeping harvesting and storage costs in line with the quality of feed produced, the potential volume of materials which might be used is tremendous.
Many experiments have been conducted to study different methods of feeding, levels of silage and combinations of silage and grain for finishing cattle. These have included a large number of general feeding experiments with different weights, ages, sexes and breeds of cattle and also more basic experiments in which the net energy value of the various rations has been determined. In general, it may be said that it takes a definite amount of energy for maintenance and gain of cattle, that is, to finish a specific group of cattle and that, within certain ranges, it doesn't make too much difference whether that energy comes from silage or grain nor what part of the feeding period they are fed. Many combinations and systems have proven to be entirely satisfactory. However, if the silage is not well-cared for and well-matured or is fed with limited or no grain, the length of feeding period will be extended.
The importance of length of feeding period varies with the type of feeder. As stated previously, for the farmer-feeder, a liberal use of corn silage will maximize the pounds of beef which can be marketed from the acreage of corn grown. He may feed only one group of cattle per year and not be concerned with keeping his lot full at all times. Other feeders may not produce enough corn to feed the number of cattle they wish to feed and may have more money invested in their feed lot. In order to maximize returns from the investment in feeding facilities, keeping the lot full at all times becomes of more importance. To such a feeder, the length of feeding period, rate of turnover or dollars invested in facilities per head fed is of considerable importance.
The level of corn silage included in the ration will also be influenced by the type of cattle fed.
Some cattle finish more easily than others. Heifers fatten quicker than steers and steers easier than bulls. Small, earlier maturing breeds finish sooner than large, later maturing breeds. These differences in ability to fatten are of importance in determining the level of silage that should be included in the ration. Cattle which finish earlier and at lighter weights will make more efficient use of high silage rations than those that require higher grain rations to finish properly.
Two experiments were conducted at the Northwestern Branch of the Ohio Agricultural Research and Development Center to compare steers and heifers when fed corn silage with no additional grain, a combination of silage and ear corn, or ground ear corn with no silage. Hereford steers and heifers from one source were fed to final average weights of 1,000 and 850 pounds, respectively. Net energy values of the rations were determined by the slaughter method in which representative animals were slaughtered and analyzed at the beginning and end of the experiment.
As expected, heifers reached their final weights sooner than steers. In all cases the heifers consumed more feed per unit of weight and, even though 150 pounds lighter, were fatter than the steers. This resulted in a greater storage of energy by the heifers and, on the average, a higher net energy value of the rations when fed to heifers. There was an interaction among rations and sexes in this regard. The net energy value of the corn silage ration averaged 17% higher when fed to heifers but there was little difference in net energy of the ear corn ration when fed to either sex.
These results indicate that, when fed without additional grain, corn silage has a higher value when fed to heifers than when fed to steers. Evidence is also accumulating that the same may be true when fed to smaller, earlier maturing cattle as compared to larger, later maturing types of either sex.
Well-eared, well-matured corn silage is the top producer of nutrients per acre of cropland. Its liberal use allows the farmer-feeder to market the most pounds of beef from his farm. Corn planted for silage should be the same as if planted for grain and should be allowed to mature prior to ensiling. Silage yields per acre and silo capacities are rather meaningless unless dry matter content is known. Although corn will ensile satisfactorily without additives, its value can be profitably improved by adding 20 pounds of ground limestone per ton of chopped corn at time of ensiling. The profitability of other additives will depend upon their effectiveness and, in the case of urea and other sources of NPN, upon their cost relative to other sources of nutients.
A number of methods for increasing the grain content of corn silage can be used. However, harvesting and storing silage and grain separately by conventional means seems most efficient and allows more flexibility in feeding. Many combinations of silage and grain are satisfactory for cattle feeding. Proportions of each included in the ration will be influenced by maximizing pounds of beef sold per acre of cropland or minimizing feedlot investment per head marketed.
When fed without additional grain, corn silage has a higher value when fed to early maturing types of cattle; such as heifers, than when fed to later maturing types, such as steers.
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This page was last updated on November 16, 2002