Silage Making

Silage is the fermented product of green forages where the acids produced by anaerobic fermentation of the sugars present in these forages are responsible for preserving them.

Advantages

• It is less at risk from the weather when compared to haymaking.
• The ensiling process is the only means by which the entire forage plant can be preserved in a succulent form. The crops can be harvested and stored at the time of its development when it has the maximum nutritive value.
• Retains high proportions of nutrients than hay because losses due to shattering and bleaching are minimized. Silage preserves 85 per cent of its energy. Hay under best conditions preserves only 80 per cent and under poor conditions 50-60 per cent.
• Silage crops have more yield than other hay-crops. Earlier cuttings at higher levels of digestibility are possible. Thus, more feed nutrients can be grown on an acre of crops used for silage than an acre used for most other purposes.
• The crop can be preserved as silage more cheaply, more quickly and with less labour.
• Mechanization from field cutting to feeding is easier with silage.
• It requires less storage space than hay.
• Fear of fire is avoided.
• Practically any forage crop is fit for ensiling. Weedy crops and crops with thick stalks can be ensiled equally well.
• Many by-products can be economically used.
• Converting crop into silage clears the land earlier.
• It is palatable and slightly laxative.
• It is a better source of protein and carotene than hay.
• There is a wider choice of feeding methods for silage.
• Ensiling ensures better storage for a long time

Disadvantages

• Requires silo and special equipments.
• Less amount of vitamin D in silage than hay.
• Additional expenses are involved for preservatives.
• Due to moisture content, tonnage and transporting charges are increased.
• Wet silage can present difficult problems of disposal of effluent.
• Smell from poorly fermented silage can create problems.
• Wastage may be high when only small amounts are made at one time.

Preparation of good silage

• Good silage should have a mild, pleasant aroma, an acid taste and a slightly greenish colour. It should be free from sliminess and mold growth and should have sufficient acid to prevent further degradation. Successful ensilage can be achieved by following the steps listed below.
• The crop should contain an adequate level of sugars for acid fermentation: Ensile forage species having naturally high sugar content, like forage, maize, sorghum and meadow fescue. Avoid a heavy content of legumes in the crop as they have low sugar and high protein contents, which favour the growth of the clostridia. Do not cut immature crops for silage making as they have high protein and low sugar contents. Crops for silage may be cut silage making as they high protein and low sugar contents. Crops for silage may be cut late in the day as sugar content increases during the hours of sunlight. When a crop is known to be deficient in sugar add molasses as uniformly as possible before ensiling.
• The crop should not have high moisture content: Avoid cutting immature crops with high moisture content, although delaying too much will reduce the digestibility of the crop. Avoid cutting crops when soaked in rain or dew. If necessary, wilt the crop in the field before transporting to the silo. Consolidate and rapidly seal the silo as the oxidation of sugars can produce water. Also, seepage of rainwater inside the silos should be prevented.
• Exclude air from silage : When the crop is filled inside the silo, air is trapped in the meshes of the forage. Oxidation of sugars takes place with generation of heat. This causes the trapped air to rise and set up currents, which draw in fresh air. Rapid filling, consolidation with a tractor, chopping or lacerating, evacuation pump for further compression of the fodder, etc. are helpful. By combining consolidation with quick and perfect sealing, the air-free condition needed by lactobacilli is quickly established while at the same time the maximum amount of sugar remains to be fermented.
• Seal the silo as soon as filling is finished. This seal will have several functions. While the silage is warm it prevents the warm air from escaping and setting in currents bringing fresh air. It also prevents entry of fresh air when the fermentation has been finished and thereby keeps the silage stable. In un-roofed silos, this prevents the entry of rain water and diluting the acid which will cause rotting of silage.
• Wilting is perhaps the most controversial aspect of silage making. Excellent silage can be made from crops with high moisture percent provided enough sugars are available for producing enough acidity. But immature crops with high moisture content are always low in sugar content also. Therefore, wilting is necessary in their case to a level of 25-30 per cent dry matter. If an additive is added, less wilting will suffice. An advantage claimed for silting is that it will increase the dry matter consumption of animals especially when animals are fed mostly silage.
• Additives: Silage making is a chemical process and, therefore, many ways of chemically preserving silage by adding certain substances have been successful. Several broad classes of additives have been tried:
  –  Those, which supply additional readily fermentable carbohydrates to produce preserving acids, e.g., molasses, sugar. Usually molasses is added at the rage of 2% of the total fodder.
  – Mineral acids (mixed hydrochloric and sulphuric acids) which give a stable, very low pH silage, and
  – Organic acids especially lactic and formic acid – which help in achieving a stable pH more rapidly. Alternatively, a culture of lactobacilli can be used.
  – Additives are not needed in making silage from crops wilted above 30 per cent dry matter or with high sugar-crops wilted above 25 per cent dry matter. They are necessary with ‘problem’ crops like those with high moisture, high nitrogen, and/or low sugar such as legumes.
  – Not only an additive reduces silage losses, it also gives an acceptable feed.
• Expose the minimum surface when silage is being fed out: When a silo is opened, air enters and mold growth will set in all over the silage face. This is negligible if silage is removed fast enough (say 15 cm per day). But wastage can occur if the face is exposed for a long time as it happens when silage is self-fed to too few number of cows. Thus, the size of the silage face may be planned for the number of stock to be fed.

Types of silos
A very large number of different types of silos are in existence. These vary from massive concrete structures with complete equipment to simple plastic bags. Other types include conventional tower silos, trench silos, pit silos, tube silos, clamp silos, wire and plastic silos and bunker silos.

• Tower silos are cylindrical concrete structures about 8-10 metres in diameter and 15 metres in height. Fresh forage is blown in at the top and when ready for use the silage is removed through a serious of openings at one side.
• Trench silos, as the name implies, is a shallow horizontal pit. Its advantage is that it is very readily accessible thereby reducing labour costs. A low matter table and clay soil are desirable in the location of trench silos. Often the trench can be dug into the side of a hill to increase accessibility.
• Pit silos, as the name implies, are pits for silage making. In large operations it involves more labour.
• Tub silos are upright of a very wide diameter. These tub silos are fairly easy to unload by hand.
• Bunker silos are suitably made in areas where soil is loose and caving in feared, and when water table is high. They are above ground structures composed of walls between which ensilage is compressed. The walls may be of wood, or concrete. Forage is put in add taken out of bunker and trench silos in much the same way. Trucks or tractor trolleys loaded with chaffed fodder can be driven in, unloaded and driven through. Forage is then packed with tractors equipped with blades.
• Clamp silos can be where soil is suitable and the water table is high. A shallow trench is dug and the soil is piled on either side to increase the height of the walls. Pack ensilage as high as possible and as compactly as possible. A good plastic seal is installed on top.
• Plastic sheets are used in different ways to produce silage. Silos of various sizes can be prepared with plastic film and welded wire fencing
• Silage bags are made of smaller tubes of plastic. They are small silos of 50 kg or even less. Thus, for small livestock operation inexpensive silage structures are available. The end of each tube is double tied making a bag with a handle at each end

Different grade / kinds of silage

• Very good silage: Silage will have good smell, pH will be 3.7 – 4.2, less than 10% ammonia of total Nitrogen. No butyric acid or moulds are present in this class.
• Good silage will have satisfactorily smell, pH 4.2 -4.5, ammonia N will be between 10-15% of total N and will contain least amount of butyric acid.
• Fair silage will contain little amount of butyric acid hence it will have slightly bad odour, pH 4.5-4.8 and ammonia N rages between 15-20% of total N.
• Bad silage will contain more of butyric acid hence it will have bad smell and pH will be higher than 4.8. This may contain more than 20% ammonia N of total N. Break down of amino acid to amine like histamine, tryptamine and phenyl ethylamine.