Silage Making ~ How to improve the nutrition of farmers’ milking animals when each family keeps only one dairy cow?
During the cold, continental winter, the major fodders available are wheat or maize straw, together with hay and concentrated feeds.
As a minimum, it is essential to provide a green fodder supplement to enhance rumen function for bovine animals. Therefore, one should develop winter fodder crops.
For smallholder farmers with limited production capacity, finding enough feed in the winter months to maintain good milk production is always a problem. Many are forced to buy hay, concentrates or silage just to keep their animals alive and are unable to benefit due to the higher prices paid for animal feed in the winter months.
Silage Making – What is silage?
Forage which has been grown while still green and nutritious can be conserved through a natural ‘pickling’ process. Lactic acid is produced when the sugars in the forage plants are fermented by bacteria in a sealed container (‘silo’) with no air. Forage conserved this way is known as ‘ensiled forage’ or ‘silage’ and will keep for up to three years without deteriorating. Silage is very palatable to livestock and can be fed at any time.
Silage Making – Why silage not hay?
Forages can be made into hay to conserve the nutrients, especially protein, before they decline in the plant. However it is often too wet to dry the successfully and special machinery, has to be used to assist the forage to dry quickly. Forage crops such as maize, are too thick-stemmed to dry successfully as hay.
Silage is considered the better way to conserve forage crops. A forage crop can be cut early and only has to have 30% dry matter to be ensiled successfully. There is no need to dry out the plant material any more than that, so wet weather is not such a constraint as it is with making hay.
Silage making is long practiced by the larger agricultural sector, but the production method relies on heavy equipment and large production, in order to dig or build storage pits and to compress the green mass, putting it beyond the reach of smallholder farmers.
Silage Making – Advantages:
Stabile composition of the feed (silage) for a longer period (up to 5 years);
Plants can be harvested at optimal phase of development and are efficiently used by livestock.
Reduction of nutrient loses which in standard hay production may amount to 30% of the dry matter (in silage is usually below 10%);
More economical use of plants with high yield of green mass;
Better use of the land with 2-3 crops annually;
Silage is produced in both cold and cloudy weather;
The fermentation in silage reduces harmful nitrates accumulated in plants during droughts and in over-fertilized crops.
Allows by-products (from sugar beat processing, maize straw, etc.) to be optimally used;
Requires 10 times less storage space compared to hay;
Maize silage has 30-50% higher nutritive value compared to maize grain and maize straw;
2 kg of silage (70% moisture) has the equal nutritive value of 1 kg of hay.
Silage Making – Disadvantages:
Silage is not interesting for marketing as its value is difficult to be determined.
It does not allow longer transportation;
The weight increases manipulation costs;
Has considerably lower vitamin D content compared to hay
Silage Making – Principle of silage making
At harvest, plant cells do not immediately “die”; they continue to respire as long as they remain adequately hydrated and oxygen is available. The oxygen is necessary for the physiological process of respiration, which provides energy for functioning cells. In this process, carbohydrates (plant sugars) are consumed
(oxidized) by plant cells in the presence of oxygen to yield carbon dioxide, water and heat: sugar + oxygen ® carbon dioxide + water + heat
Once in the silo, certain yeasts, molds and bacteria that occur naturally on forage plants can also reach populations large enough to be significant sources of respiration. In the silage mass, the heat generated during respiration is not readily dissipated, and therefore the temperature of the silage rises.
Although a slight rise in temperature from 80° to 90°F is acceptable, the goal is to limit respiration by eliminating air (oxygen) trapped in the forage mass.
Some air will be incorporated into any silo during the filling process, and a slight increase in silage temperature is l kely. These temperature increases can clearly be limited by harvesting at the proper moisture content and by increasing the bu k density of the silage. Generally, it is desirable to limit respiration during the fermentation process by using common sense techniques that include close inspection of the
silo walls prior to filling, harvesting the forage at the proper moisture content, adjusting the chopper properly (fineness of chop), rapid filling, thorough packing, prompt sealing and close inspection of plastics for holes.
Silage Making – Some materials used for silage
Maize stalks/corn stover
Agro industrial-by products such as spent malt etc. (moisture content should be between 65-70%)
Silage Making – When to cut materials for silage
Maize and sorghum should be cut when grains are still soft and milky, whiles grasses and legumes are cut at flowering stage. This is the stage when the plants abound in protein, carbohydrates and mineral salt and vitamins. Sorghum should be cut at the right time to avoid prussic acid and poisoning.
Some important tips to consider:
It is important to use quality fodder materials to obtain quality silage. This is because silage does not improve the quality of fodder being ensiled.
There are three necessary conditions that must be observed:
- Cut and ensile the fodder quickly
- Pack very tight to avoid pockets of air in the trench/pit
- Seal appropriately. Make sure water or air does not enter the trench/pit either from rain or from ground water
Silage Making – Dry matter and moisture
Ideally, corn silage should be harvested at the moisture content appropriate for the type of silo used.
Recommended moisture contents are 65–70 percent for horizontal silos, 63–68 percent for conventional tower silos, 55–60 percent for limited-oxygen silos, and 65 percent for silo bags.
Corn silage yield and quality as influenced by growth stage.
Maturity Stage Moisture %
Early dent 73
No milk line 60
Delaying harvest can reduce both the fiber and starch digest bility as the stover gets more lignified and the over mature kernels become harder and less digestible if left unbroken after ensiling. Corn that is ensiled extremely wet will ferment poorly and lose nutrients by seepage, which also has potential to damage the silo and if not contained, contaminate local water supplies. Another problem with chopping silage with too much moisture is that a larger amount of lactic acid is needed to reduce the pH.
This results in a longer period of time before the silage becomes fermented, producing a lower quality silage. Silage that is too dry may result in poorly packed material, causing more mold and spoilage due to air trapped in the silage. In dry, over mature corn silage, the stover portion of the plant is less digestible and contains lower amounts of sugars and vitamin A.
It will not pack well in the silo, more oxygen will be present and it will take longer to get through the aerobic phase into the anaerobic phase of fermentation. Nutrients will be used for respiration during the aerobic phase, the temperature of the silage will increase and possibly burn.
|Parts of plant||Dry matter in early wax ripening phase (%)||Dry matter in early wax riping phase (%)|
The approximate moisture level of chopped silage can be determined by means of a “grab test.”
Squeeze the chopped forage tightly into a ball for 20 to 30 seconds, and then release quickly. Forage chopped into 3/8 to 1/2-inch pieces should be used.
Dry matter is the most important factor for production of good quality silage. The optimal quality silage is produced from components with dry matter contents ranging between 30 and 35%.
In the following table the percentage of moisture in different parts of the maize plant are shown, as well as the ideal time for harvest for silage preparation.
|Condition of the forage ball||Approximate moisture content|
|Ball holds its shape and there is considerable free juice||Over 75%|
|ball holds its shape but there is very little free juice||70 to 75%|
|ball falls apart slowly and there is no free juice||60 t0 70 %|
|ball falls apart rapidly||Below 60 %|
Increased moisture or lack of dry matter in silage components should be avoided when possible, as the activity of the lacto-acidic bacteria is decreased and the activity of the butyric acid producing bacteria is increased. The optimal quantity of dry matter is achieved in the last phase of vegetation of the plants.
When the weather conditions do not allow timely harvest, resulting in too wet or too dry silage materials, the desired moisture can be achieved by mixing dry and wet components. The composition of the dry and wet components is also determined through use of the Pierces’ square as show below:
If you are producing silage from whole maize plants and freshly harvested alfalfa. In the middle of the square you indicate the desired dry matter contents of the silage (for example 30%). On the left side of the square in the upper corner, you indicate the dry matter of the fresh alfalfa and in the lower square, the dry matter of the whole maize plant (45%).
By deducting the smaller numbers from the bigger ones, you get the needed percentage of each component that has to be combined in order to achieve the desired dry matter contents. In this case the fresh alfalfa should be included with 15 parts, or 60% and that of the whole maize plant, 10 parts, or 40% of total quantity, resulting in average dry matter of 30%.
Silage Making – Combined silage
If more crops are available, it is highly recommendable to produce silage trough combining of more products or by products. The most economically feasible results are obtained when low quality components, (crops that cannot be silaged on their own, such as fruits and leafs of sugar beat and sunflower) are added to more qualitative components (maize, alfalfa etc.) up to 30%.
As an example, high quality silage can be produced from whole plant of maize (45%), maize cone and grain (25%) and fresh alfalfa (30%). Leafs and fruits of sugar beat can be also used for preparation of combined silage, as they contain sufficient sugar percentage (4-6%). The best combination is sugar beat leafs and fruit, together with whole maize plants or maize straw. A main success condition is that the sugar beat does not have much earth in it.
When you combine sugar beat with whole maize plants for silage production, it is best to use maize plants in a later stage of vegetation. The sugar beat contents depends on the dry matter of the maize plant and usually in the total mixture contributes with 25-30%.
Silage Making – Silage production from drought affected crops
When corn is so drought stressed that it may not resume growth, it should be ensiled. Corn in this condition usually has few ears and has leaves that have turned brown and are falling off. The net energy content of drought damaged corn often is 85–100 percent of normal, and it sometimes contains slightly more crude protein. Drought stunted silage often contains high fiber digestibility, so when it is supplemented with additional grain, it can be an excellent forage and sustain high milk production.
One concern with drought-stressed corn is the potential for high nitrate levels in the silage. High nitrate levels are found where nitrogen rates were applied and when a drought-stressed crop was chopped within three days following a rain. Ensiling crops that are suspected to have high nitrate levels is preferred to green chopping, because fermentation will decrease nitrate levels by about 50 percent.
High temperature and drought causes accumulation of nitrogen in plants. Which affects significantly the conversion of the feed. The lactic acid produced when silaging reduces the nitrogen content in plants.
Silage Making – Silage production from frosted corn
Corn is occasionally damaged or killed by frost before it reaches the desired maturity for ensiling. If the frost is early and green leaves remain on the plant, the crop will continue to accumulate dry matter and should be left in the field until it reaches the appropriate moisture content. Plants that are killed and still immature will likely contain too much moisture for immediate ensiling.
These plants will dry slowly and dry matter losses will increase as the dead plants drop their leaves in the field and sugars leach from the frosted leaves. The best option is to leave the crop in the field to dry to an acceptable level (at least 72 percent moisture for a horizontal silo), unless it appears dry matter losses are becoming too high or harvesting losses will increase dramatically.
Silage Making – How to dig a trench/pit
The trench/pit should be dug in a well-drained area/ground such as hill side (concreted pit/trench is preferred).
The size of the trench/pit depends on the quantity of silage needed.
A drained ditch/gutter depends should be dug on the upper side of the trench/pit to prevent run-off from entering.
Silage Making – Steps to follow
- Dig a pit/trench
- Cover the floor and sides of the trench/pit with plastic.
- Harvest and chop the fodder material into pieces (about 3-5cm)
- Put the chopped fodder material into the trench/pit in layers whiles you compress it.
- Pack and compress every layer till the trench/pit is filled.
- Cover the trench/pit when it is full, first with plastic and then a layer of soil to make it air tight.
Some effluent may come out from the silage after a few days which is normal.
The silage will mature for use in a month or two (1-2) but can stay for over a year once it is not opened. Normal matured silage when opened has a sharp smell (but not unpleasant). It is yellowish green or light brown in colour.
To feed silage to stock, open and scoop quantity needed and cover well with the plastic again.