Post date: Oct 3, 2012 6:43:48 AM

What is Silage?

Silage is cut green plant material that is sealed in a concrete pit without air and water. Silage can be stored for approximately two years and still have up to 85% of the energy and protein value of the original fodder crop.

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Why make silage?

The major fodders during the dry season are crop residues and poor quality roughages. Green fodder is needed to enhance rumen function. Excess high quality fodder can be preserved for use during the dry season. Excess forages can be conserved as hay or silage. However, ensiling generally produces better quality roughage than hay because less time is required to wilt the feed, causing little reduction in feed quality. Hay making requires a longer period of rain-free days, which are often rare in many areas during the wet season when feed excesses generally occur. During the wet season, tropical forage species grow very fast, with forage yields often exceeding animal requirements. If not cut and fed to animals, it will continue to grow, producing very long fibrous material, low in feeding value. Silage making is a viable option under such circumstances. If cut plant material is stored with air and water it becomes rotten and can be used as fertilizer but not animal feed. There are three main roles played by silage making. These are:

1. To build up feed reserves for utilization during periods of feed deficiency, e.g. dry season.

2. As a routine feed supplement to increase productivity of animals.

3. To utilize excess growth of pasture for better management and extended utilization.

4. Silage quality is maintained for longer than is hay quality, because hay oxidizes during storage. Thus silage is better as a fodder bank than is hay.

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Types and sizes of silage storage systems

The principles of silage making are the same regardless of size of operation; the major difference is in the type of storage used. There are many ways to store silage. Silage pits or heaps for smallholders should be small. Making bag silage is another option to make small quantities of silage that can be fed out in a short time (1 or 2 days) without spoilage.

How much silage should be made?

The quantity of silage to store depends on several factors such as how many animals are to be fed, how much they are to be fed, for how long they are to be fed, the storage space available, the amount of excess feed to conserve, forage DM content, available labor, etc. The following example shows the calculations for total silage requirements for a smallholder sheep farm. Assume that a farmer has 10 sheep that need to be supplemented for 90 days on 1 kg fresh material at 20% dry matter (200 g silage DM/d) for each sheep.

To calculate total silage requirements:

10 sheep x 1 kg/ sheep/day x 90 days = 900 kg fresh silage required.

In most storage systems, there will be a loss of about 15% due to fermentation.

Consequently, the fresh weight that needs to be stored for the total of 900 kg required is:

1. 900 kg divided by 0.85 = 1059 kg fresh silage for 90 days.

2. This is equal to 1059/90 = 11.8 kg fresh silage/day.

3. If the farmer is using plastic bags to make silage, he will need silage stored in 2 plastic bags of size 30 x 30 cm (see Table 1 for capacity of plastic bags) each with a capacity of 4-6 kg to feed his sheep daily. He will need 180 bags for the 90-day feeding period. The typical weights of silage in various types of storage are listed in Table 1. Weights will vary widely according to content of material, chop length, type of material ensiled and how well it is compacted.

Table 1. Weights of chopped silage in various types of storage

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Requirements to make good silage

Silage making is useful only if the ensiled product is of good quality, i.e., well-preserved and of high digestibility and protein content. The main requirements are:

The fodder should be harvested at a young stage of growth. Fodder should contain enough sugars for fermentation. Tropical grasses are inherently low in soluble carbohydrates, with the exception of maize and sorghum species. If the material is of adequate quality, but lacking in sugars, molasses or another source of sugar may be added. The material to be ensiled should be easily compactable and covered to exclude air. Chopping before ensiling will help to compact the material.

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Fodder for silage making

The quality of silage depends on the fodder being conserved, and applies equally to silage made in bags. Fodder with high sugar content conserves well. Problem fodders include mature grasses harvested in the rains and legumes in general. Wet grasses and legumes must be wilted before ensiling. Additives, which may be used to enhance fermentation or sterilize the crop, may be added. Anycompound for smallholder use must be cheap, not toxic or corrosive, and easy to apply. Molasses is such an excellent additive where available. In India maize /corn is used for making silage. African tall variety of maize / corn is a good fodder crop as it gives good quantity of yield per acre. Silage bags are not commonly available in India.

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Basic Method of Silage Making

(Silage Making)

Harvesting fodder to be ensiled

Harvest at the optimum stage of maturity: One of the main advantages of harvesting silage is that timely harvest is usually possible. The quality of silage depends upon the stage of harvesting. The stage of plant growth at harvest mainly affects the amounts of digestible protein and energy.

Recommended stages of harvest are:

Legumes and grass legume mixtures, when legumes reach the 10% bloom stage.

In general, grasses should be harvested just before flowering.

For maize /corn, which is largely used for silage making in India, appropriate time for cutting is 65-75 days or 15 days after crop coming.

Moisture content: The crops should contain about 30-35% dry matter at the time of ensiling. If moisture content is high, first wilt the crop to 30-35 % dry matter content by spreading the fodder. Wilted silage should produce little or no effluent. Unwilted silage will produce some effluent, which may leak out and cause spoilage especially in case of bag silage. At higher moisture levels, seepage or a sour fermentation can occur and at lower levels, the silage will heat or mold, or both. A useful field method to check that the moisture level is right is called the squeeze test. Start by chopping some forage as you would to fill the silo. Then grab a couple handfuls of chopped forage and squeeze them tightly in your fists for about 30 seconds. Does free juice run or drip from your fingers? This forage is too wet for proper ensiling. Wait a few days to chop and try again or wilt. What if it doesn't drip? Then, slowly open your hand. Is your hand barely damp and does the ball of forage start to fall apart quickly? This forage is too dry and is likely to heat and spoil in the silo. Add some water or find wetter forage to mix with it. When you release your squeeze, if your fingers and palm are moist and the forage ball holds together, the forage is just right for chopping.


Chop the fodder into small pieces (1-3cm) before ensiling. Chopping makes it easy to compact the silage and to remove the air. The fodder can be chopped by hand, with a large knife / 5 guillotine, or using a chaff-cutter with a rotating blade if available. By making bag silage throughout the growing season, harvesting and chopping fodder by hand is feasible. But for commercial sheep or goat farming hand cutting is not feasible. In that case motorized chaff-cutter of 5hp or above should be used.


Fill the chopped fodder into one of the concrete pit layer by layer without making any air gap in it. When using pit for ensiling, gently but firmly stamp or press on the fodder layers by using some planks to expel air. After filling compressed fodder in the pit cover the top part of pit very tightly without any air gap. Multiple layers of plastic sheets are advisable. Again pit should be covered tightly as possible. This will compact the silage. Then seal it from air.

Packing / Compaction

Packing is necessary not only to get the air out, but more important, to keep it out by excluding air pockets.

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Why is whole crop becoming increasingly popular in the dairy sector?

• Increased Dry Matter Intakes from a second or third forage

• More milk per cow (8-10% increase in yield)

• Option for more efficient production with more liters from forage

• Higher energy levels with 30-35% starch

• More long fiber to stimulate rumen - “Scratch Factor” (see reverse)

• Alternative use for cereal crops lower cereal prices

• Well suited areas of the UK where maize production is marginal

• Ideal entry for an early grass re-seeds

Top 10 tips for making good whole crop silage from cereals

1. Use the best cereal crops: A poor crop of wheat or barley will make poor quality whole crop. Keep the crop free from weeds and disease

2. The correct cutting date is critical for good whole crop silage and growth stages change very quickly at harvest. Fermented whole crop wheat is usually harvested by using a precision (short) chop harvester fitted with a combine header, while grain for crimping is processed using specialized machinery

3. Cut a fermented cereal whole crop when the grain is at the soft/cheesy stage:

(GS. 77-85 ) at about 30-40% DM There will still be green in the stems (50% green - 50% yellow)

4. Once at the correct growth stage DON’T DELAY: Growth stages change rapidly and DM can change by 2% per day so cut without delay! Go early rather than late

5. Cut High: Cutting height of about 4 inches leaving rubbish in the bottom

6. Short chop length: to aid consolidation

7. Use quick action POWERSTART silage inoculant to ensure the whole crop is fermented as quickly as possible: POWERSTART is fast acting - preserving more of the nutrients and producing a stable whole crop. More sugars, more protein and less ammonia give a more palatable forage

8. Fill the clamp fast, evenly and roll as you fill, minimizing the length of time exposed to air: Work into thin layers and roll well. Clamps should be long and narrow. i.e. narrow face for faster feed out and minimal waste, avoiding aerobic spoilage.

9. Roll for half an hour maximum in the evening and sheet down every night: It takes just 20 minutes to use up all the oxygen in silo, then fermentation begins if no more air is getting in.

10. Completely seal the silo and weight down shoulder and top sheets as soon as possible

What is “scratch” factor?

The rumen is full of bacteria that break down and digest fibre (cellulose). The pH of the rumen must be between 5.5 and 6.5 for the bacteria to survive and function properly. If pH drops to below this then the bacteria will not work which leads to an increasingly acid rumen and eventually leads to acidosis, poor appetite and poor intakes. Long fibre in the diet (straw/grass/silage) stimulates the cow to chew the cud. It does this by scratching the rumen wall causing muscle contraction and the cow to regurgitate her food (chew the cud). Chewing the cud causes the cow to produce large amounts of saliva. Saliva contains Sodium Bicarbonate, which buffers the rumen helping to keep the pH at 5.5 - 6.5. Forage such as cereal whole crop containing some “long fibre” which stimulates the rumen in this way is said to have a higher “scratch factor”.

A typical Wholecrop analysis -fermented

Dry Matter 30-40%

ME 9 – 11MJ/kg

Crude Protein 9 –11%

pH 4.0 – 4.6

Ammonia 5 – 8%

Estimated yield:

1-15 tonnes per acre depending on variety, cutting height, dry matter, winter or spring sowed seeds.

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