When green fodder are in plenty they are conserved as either silage or hay to meet the demand of good quality fodder during lean season. Silage can be defined as a green material produced by controlled anaerobic fermentation of green fodder crop retaining its moisture content. Silage is the green succulent roughage preserved more or less in its original condition, with a minimum deterioration and minimum loss in respect of various nutritive constituents of fodder. The process of conserving green fodder is called as ensilage. Silo is the receptacle in which silage is made. The best silage are moist to the touch, soft but not slimy and fragrant in their own characteristic way.
Green, fruity silage Is the most palatable and nutritious type. This can be produced only under careful management from crops that are cut at the right stage with a dry matter of 25 to 35%. A dark-brown colour indicates excessive heating.
Crops Suitable for Silage Making
- Kind of crop
- Cops rich in soluble sugars/carbohydrates are most suitable for ensiling; e.g maize, jowar, bajra.
- Cultivated and nature grasses can be ensiled with edition of molasses at 3 to 3.5%.
- Mixture of grasses /cereal fodders and legumes such as berseem, lucerne etc. in a ratio 3:1
- Unwilted leguminous leafy fodders and dry forage in the ratio of 4:1.
- Stage of Hervesting
Crop should be harvested between flowering and milk stage. In general, cops with thick stems are conserved in the form of silage while thin stemmed crop are conserved as hay.
Preparation of Silage under Field Conditions
Silo: A silo is an air tight structure designed for the storage and preservation of height moisture feed as silage. Pit silos are more common in India. The pits are due 2.4 to 3.0 m deep, with variable sizes. One cubic metre of space is required for 400kg fodder.
Requisites of a silo
- The walls should be impermeable so that water can’t gain entry in to silo pit. Walls may be made of cement or brick and mortar.
- Silo should be sufficiently deep. It should not be shallow. The depth depends on the water table in the locality.
- Silo must be located on an elevated ground.
- The size of the silo should be calculated on the basis of the number of animals to be fed, the length of feeding period.
Method of preparing silage
- Select the crop that is to be ensiled when it has 30-35% dry matter. In case the crop has less than 30% dry matter allow it to dry for 3-4 hours so that the dry matter content would increase to 30-35%.
- Generally the crops are harvested and ensiled when the ears starts coming.
- Select the days of the week when the weather is fair and not rainy.
- Silo can be filled with long fodder as well as with chopped fodder. It is always better to chop the fodder first since packing is batter. Thus loss of nutrients is minimized with chaffed fodder. Further, filling and removal of silage is easier.
- After chaffing and ensuring that dry matter is around 35% the silo is filled with fodder.
- The fodder should be evenly distributed throughout the pit. Trampling should be done properly either with men or tractor or bullocks should be packed 3-4 feet above the ground level.
- From all the sides it should be covered with long paddy straw/grasses (over the green fodder) may be about 4 to 5”. The silage would be ready in two months after covering.
- Salt at 0.5%, urea at 1% are added to cereals and grasses to improve the palatability and nitrogen content. In grasses silages, molasses is added to 3 to 3.5% to improve the suger content thus quality of silage. In a more mature crop higher level of molasses (5%) may be added.
Important Conditions for Success in Silage Making
- Storing the plant material at a moisture content of 65 to 75%.
- Excluding air.
- Encouraging a rise of temperature to 30 to 38°C. When it is not possible to secure these optimum conditions, it is helpful to add some preservatives or ‘silage conditioners’. Molasses, Salt, cereal grains, citrus pulp act as preservatives and enhance feeding value. Sodium matabisulphite modify fermentation process and reduce the smell.
Nutrient Content of Silage in Comparison to the Green Fodder
The ash, ether extract, crude fibre, crude protein, and NFE contents of silagecanbe very similar to the crop from which the silage was made. Proper amounts of moisture and fermentable carbohydrates and proper storage influence the ensiling process and the nutritive value of the silage.
Under optimum conditions
- The soluble carbohydrate fraction is almost entirely converted to organic acids, principally lactic acid and smaller amounts of the volatile acids, and
- The protein is converted to amino acid.
Silage can greatly influence the loss of oxidizable vitamins. Carotene is fairly easily oxidised. Vitamin C or ascorbic acid is easily decomposed under the conditions prevailing even in the best-made silage. When oxidation and temperature are controlled a large proportion of carotene is conserved in silage. In a good quality silage (pH 4-4.5)β-carotene appears to be relatively stable and thus losses are likely to be low.
A part of the minerals may be leached out and lost, but a large proportion will remain unchanged or simply take part in some new combination.
Silage quality:Shephered et al. (1948) have classified the silage in to the following categories.
- Very good silage: Silage having acidic taste and odour, being free from butyric acid, moulds, sliminess, showing a pH range of 3.5-4.2, and with ammoniacal nitrogen less than 10% of the total nitrogen. Lactic acid content is 1-2%
- Good silage: Silage possessing acidic taste and odour, traces of butyric acid (less than 0.2%), Ph 4.2-4.5 and ammoniacal nitrogen 10-15% of the total nitrogen.
- Fair silage:Ensiled material with some butyric acid, a slight proteolysis, some moulds, pH 4.8 and above and ammoniacal nitrogen 20% of the total nitrogen.
Haylage: When grasses and legumes generally meant for hay are ensiled the term ’haylage’ Is used. Material wilted to 40-45% dry matter before ensiling is often referred to haylage. The dry straws are improved by the addition of suitable additives namely urea, mineral mixture and water. The straws are chaffed into fine pieces (2-3cm). One kg of urea and 1.5 kg of mineral mixture are dissolved in 20kg of water and mixed with 97.5 kg of the chaffed material. This is stored in silo pits like silage and is allowed to ferment under anaerobic conditions. The soluble carbohydrates present in the dry straws act as a source of energy for the bacteria to grow well. After about two months the pits are opened and fed to livestock. It is supplemented with 2kg of green fodder per day per animal to take care of the requirement of vitamin A.
Wastelage: A silage containing animal organic waste (poultry dropping, poultry litter, swine excreta, bovine dune) is called wastelage. Wastelage is anaerobically fermented animal waste containing other feed ingredients with the help of lactic acid producing bacteria.
Example: Ensiling of paddy strew /jowar or maize with animal waste.
Mixed in about 22 litres of water. This is sprayed on straw.