SILAGE PREPARATION FOR DAIRY ANIMALS
SILAGE is the term used for the product formed when any green plant , material is put in a place where it can ferment in the absence of air .The major changes which occur during ensiling are the fermentation of sugars to form acids and the breakdown of some of the forage proteins to simpler compounds, including ammonia .This fermentation occurs during the first two to three months; after that the silage, remains practicly unchanged for another 12 to 18 months. The process of making silage is called ensiling, and the container for keeping silage as, silo.
Silage preparation is one of the important methods for storage of green fodder for dairy animals & it is necessary to adopt this method by Indian dairy farmers on large scale in situations like drought or heavy rainfall or scarcity of fodder.
Silage making means preservation of chaffed cereal green fodder in anaerobic condition by way of fermentation method. In anaerobic condition (no air inside pit/tank),with the help of micro organisms, sugar contained in green fodder is converted in to Lactic acid ,which help to preserve the green fodder for longer duration. Respiratory function of living cells present in green chaffed fodder utilises Oxygen in air tight condition & releases water & carbon dioxide in closed environment in pit/tank. Due to Carbon dioxide releases in pit/tank, air inside is expelled outside as well as organism which depends on oxygen (Like bacteria & Fungi) cannot withstand in CO2 atmosphere in Tank/Pit. These effects in to preservation of chaffed green fodder in silo pit/tank as silage for longer duration (6 months or max. a year if good care is taken).
The advantages of silage making are as follows : ——
(i) crops can be ensiled when the weather does not permit curing them into hay or dry fodder;
(ii) the use of silage. generally makes it possible to keep more animals on a certain area of land;
(iii) at a low expense silage furnishes high-quality succulent feed for any season of the year;
(iv) from weed crops, which would make poor hay, satisfactory silage can be produced; the ensiling process kills many kinds of weed seeds;
(iv) crop from a given area can be stored in ,less space as silage than as dry fodder; silage contains 230 kg of dry matter/m3 as against 66 kg/m3 in hay;
(v) stemmy forage crops when converted into silage become soft and are better utilized by the stock; and
(vii) many undesirable things present in a fresh crop are eliminated after ensiling.
CHARACTERISTICS AND CLASSIFICATION OF SILAGE———
Silage quality is a measure of ensiling process, the amount of nutrient loss and relative palatability.
Physical properties———-
Colour. ————
Colour is an important index of quality. A good silage should be yellowish green. Dark-brown or charred black material often found is usually the result of excessive heating, poor packing and sealing or too Iowa moisture content. If the moisture content is too high the silage usually appears deep green to black. Mould formation occurs in the presence of air.
Odour and texture.————-
Good silage does not have a strong, objectionable odour. It is pallatable to livestock. However, it should be fed carefully to cows to prevent off-flavour in milk. Strong butyric acid ammonia or musty odour indicates a considerable loss in feed value. Silage of this type should be avoided if possible. Very wet silage usually have strong odour, indicating inferior quality. The addition of preservatives or careful wilt1ing may ensure proper fermentation and a more desirable odour. Silage containing stubble and foreign matters or fodder cut at too late a stage will naturally be Jess palatable and nutritious.
Degree of wetess. ———–
Silage having high moisture content (75 per cent or more) contains less feed value per kilogram than silage having low moisture. This may be due to the loss of nutrients through seepage. If juice runs freely when silage is squeezed in the hand, it !indicates that the material has high moisture content.
Chemical properties ———-
The chemical composition of silage depends upon types of crop. method of ensiling, compaction, etc. The quality of the silage is most readily assessed by determining its pH value, which should be less than 4.2. With this degree of acidity, there is almost invariably more lactic (3 to 13 per cent of (he dry matter) and volatile acids, and butyric acid ,is present only in traces. In general the butyric acid concentration of good silage is less than 0.2 per cent and the ammoniacal’ nitrogen content less than 11 per cent of the total nitrogen
STEPS FOR MAKING GOOD SILAGE———–
1.A void bad weather at the time of harvest—–. One should avoid the rainy days. In the rainy days, the• crop will be too wet and it will be difficult to complete the whol~ operation of harvesting of crop, filing and sealing of silo, etc.
- Assess the quantity of crop to be harvested.— Quantity of harvested crop will depend upon the number and kind of animals to be fed, and on , the length ,of feeding period. The number and size of silo pits have to be regularized accordingly so that there can be a regular supply of feed particularly during lean months.
- Check the condition of silo.– The walls must prevent the entrance of air and the doors (in case of tower silo) must fit snugly. If air enters, moulds will grow and spoil the silage. The silo walls must be smooth, perpendicular, strong and rigid. If the walls are not smooth and perpendicular, cavities will form along , the walls as the mass settles, and the adjacent silage will get spoiled. The walls must be strong and rigid to withstand the outward pressure on walls exerted by the silage when it settles.
- Growth stage of the crop–. The crop should be neither dry nor ‘ have high water content. In the former case it will not pack well in the silo, and in the latter case the silage is apt to be very sour, .or it may even be spoilt. For preparing good silage, forage crop with solid stems should be selected so that only a small amount of air will remain in the mass after it has settled. If hollow-stemmed crops are used, the cut forage must bc trampled with special care to force out as much air as possible. The type of crop affects the quality of silage, but the condition of crop affects the quality even more.
- Pre wilt the forage if needed—. The practice of wilting the crop in the field for a few hours before ensiling is valuable for young succulent grass or legumes. The moisture content should not be more than 70 to 75 per cent. It encourages butyric acid type of fermentation; further, the amount of liquid effluent from the silage is reduced.
- Chop the crop if needed.—- For proper consolidation the crop should be chopped into short lengths before ensiling. When chopped, the proportion of the material immediately available for bacterial fermentation is much higher and consequently acid production occurs much more rapidly. Chopped pieces should not exceed 4 to 5 cm length.
- Decide mixtures of legumes and other forage crops ahead.—- Good silage can be made from a mixture of legumes such as alfalfa or soybean with a suitable proportion of green corn or sorghum, maize and cowpea mixture, paddy straw with berseem, etc., which may contain much more sugar. The mixture can be in the following ratio:
Sorghum + alfalfa, 1: 3; paddy straw + berseem, 1 : 5; paddy straw + water-hyacinth, 1: 4; and maize + cowpea, 1: 3. - Addition of molasses, salt, etc.— Addition of molasses to leguminous forage crops improves the quality of silage. Salt adds taste to the silage.
- Proper filing of silo.—– To ensure good silage, it is very essential that the chopped material is distributed uniformly throughout the silo. The material should be trampled, especially well near the wall, as the friction with the wall retards settling. It is believed that keeping the centre higher than the outside while filling the upper part of the silo lessens the tendency of the silage to draw away from the wall as it settles. To avoid a large amount of spoilage at the top, for the last few metres the silage should be levelled off and trampled thoroughly. It will be better if levelling, trampling, addition of additives, etc., are done after every 30-cm layer of packing. No matter what the method followed is, if the forage is too dry water should be added.
- Cover;ng and sealing of silo.—— Once the pit is full it should be covered with wet straw, sawdust or other materials, and plastered with l5-30-cm-thick layer of soil. The loss at the surface can be reduced to a minimum if the forage is covered (after it is levelled and well trampled) with cheap roll roofing (like polythene), the joints being lapped about 10 cm and the ends turned up against the side wall to l3 cm. After covering, weights such as paving slabs, concrete posts, concrete cylinders and wooden logs should be kept for better compression. Finally, a thatch of straw, reeds, or bracken should be added whenever possible, and, if not, a simple roof of some kind should be devised to keep off the rain.
11.. Intermediate checking of silo.—- It is advantageous to check the seal from time to time, flatten it down and seal any cracks. There should be a small door near the ‘surface of the silage to allow the ,carbon dioxide to escape. Very rarely, poisonous yellow nitrogen dioxide gas is formed in silage soon after filling, apparently being produced from nitrate in the forage
Method of feeding silage and a point to note ———-
(1) Since the nutritional ingredients of silage varies greatly with the kind, mixing ratio, and moisture content of the raw materials, it is important to analyze feed, and carry out appropriate feeding to cattle. (2) Pasture plant silage should be fed together with other roughage such as hay, although it can be fed alone. (3) In general, whole crop silage is not fed by itself. It is because this silage contains high nutrients (TDN), if it is fed too much females will become fat and tend to be infertile. (4) If the number of animals suffering from diarrhea increases, as it might be possible that the silage has deteriorated in quality, and feeding should be stopped. After discarding the deteriorated parts, feeding may be restarted. (5) When keeping on feeding a large quantity of silage having a high concentration of nitrate nitrogen (2,000 ppm or higher in DM), it is needed to pay close attention because females might develop infertility, abortion, sudden death, etc. Silage with a high concentration of nitrate nitrogen is sometimes found when pasture plants, corns, etc., to which too much manure was applied, is harvested (especially early cutting) and processed. If there is a possibility that the silage might contain high concentration of nitrate nitrogen, it is preferable to check the concentration beforehand (it can be simple to do with an indicator drug). Depending on the result of the check, the silage may be discarded, or given with a reduced ration by combining it with other roughage (straws, etc. having low nitrate nitrogen concentration)
Judging the quality of silage———
The quality of silage can be judged by its color, smell, taste and touch. (1) Color: In general, pale yellow indicates good quality. If the color is from dark brown to dark green, the silage underwent bad fermentation and is of bad quality. (2) Smell: Acidic or a sweet-sour pleasant smell indicates good quality. On the other hand, if there is a manure smell or putrid smell and it is so repugnant that one cannot put the silage near one’s nose, the quality is poor. (3) Taste: If the silage tastes sour and there is no problem in putting it in one’s mouth, the quality is good. On the other hand, if the silage tastes bitter and one cannot put it in one’s mouth, the quality is poor. (4) Touch: When squeezing the silage tightly in a hand and then opening the hand, if the silage breaks slowly into two, that silage is of good quality. If the silage breaks into small pieces separately, the silage is deficient in moisture content. If water is dripping, the moisture content of the silage is too high.
Essential fodder crops for silage making———–
To prepare best quality silage, cereal green fodder like Green fodder maize, Fodder sorghum, Bajara, Hybrid Napier, Sugar cane tops, Oat, Marwel etc are required. Preference for cereal green fodder (monocotyledons) is due to it has more sugar content than protein, as sugar is utilised in fermentation process to make lactic acid by microorganisms. These cereal fodder crops have hard stem, which takes more time for drying in making hay of these crops, so it is better to use these kinds of crops for making silage than hay.
Benefits of silage making————-
• Silage is storage system of green fodder which keeps all parts of fodder in appropriate condition for feeding than any other system of storage of fodder.
• Silage requires less space for storage as it is pressed in pit/tank than hay making.
• For daily cutting, transporting & chaffing of fodder in traditional way requires more labour &time but in case of silage, fodder cutting, transport, chaffing is done at one time only, so it is less labour & time consuming practice. Land under fodder cultivation is emptied, and immediately it is used for plantation of other crops. So farmers’ can take more crops in same land in a year against traditional way where land is reserved for fodder until all crops is harvested.
• Silage is prepared in closed & air tight condition so there is no danger of fire. (In hay making, dry fodder is stocked & exposed for fire like situation)
• Due to lactic acid in silage, it is easily digestible to animals, so energy required for digestion is used for other purposes like milk production.etc.
• Silage is tasty & flavoured, so it increases appetite of dairy animals.
• Important thing behind to adopt silage is in scarcity it provide supply of fodder to dairy animals. Situations like drought, high rainfall & scarcity of fodder, farmers may use silage for feeding to dairy animals. (Rain fed area where shortage of green fodder is for March to June & in high rainy area or water logged lands, it is impossible to cultivate or harvest fodder)
• Due to treatment of additive for silage, farmers can supply energy, mineral & vitamins to dairy animals.
Planning for silage making————
There are two methods for silage making which are vastly used i.e. Pit method or tank method. These two methods are economically viable for dairy farmers. For planning of silage, following aspects needs to pay attention-How many dairy animals farmer’s have? How many days farmer’s have to feed animals with silage? Is sufficient green fodder is available with farmer to prepare required silage? On the above points, decide to plan for silage making, there is example for you- -One dairy farmer has four adult milching dairy animals. He has to plan for silage for four summer months (i.e. March to June), so go through following points- There are four milking dairy animals Farmers have to make silage for four months i.e. 120 days Maximum per day feeing of silage is 20 kg per animal so per day feeding for four animals as 80 kg. So for four months i.e. 120 days for four animals requirement of silage is 9600 kg.This means 9600kg of chaffed green fodder is require to make silage for four dairy animals for four months. In one cubic foot in pit or tank (1 cubic foot = 1 foot long × 1 foot wide × 1 foot high),contains 16 kg of chaffed green fodder. To decide dimension of pit/tank for 9600 kg chaffed green fodder ,you may divide it with 16 kg, so you may have to make 600 cubic feet of pit/tank as 20 foot long × 6 foot wide × 5 foot high.
Pit/tank method for silage making-————
Depending upon local situation like ground water level, number of animals & duration of feeding silage to animals, decide shape & size of constructing pit/tank for silage making. For pit method, select location for making pit at higher level on ground so that rain waer may not percolate in to pit. In rectangular pit, corner edges should be making round so that while filling & pressing chaffed fodder, air will not remain inside in the corners of pit or tank. Wall of pit/tank should be air proof to avoid air too come inside in pit /tank through cracks or crevices .To avoid this situation, plaster wall of silo pit or tank with cement or moistened soil. If ground water level is nearer, then go for building tank for silage making than pit method. If plastering cement to the wall of pit/tank is uneconomical, then you may use HDPE plastic paper (200 micron) to cover pit/tank inside out position.
Treatment for Silage———-
• For making best quality & balanced silage, needs proper treatment of additives like-
• Per ton of chaffed green fodder requires 1 kg Urea, 2 kg jaggary, 1 kg common salt, 1 kg mineral mixture & 1 litre of Whey.
• Prepare separate solution in 15 to 20 litres of water for Urea, Jaggary, Mineral mixture & common salt in separate pots/buckets & then spread it on layer of pressed chaffed green fodder while filling silo pit/tank.
Procedure for filling silo pit/tank——————
When fodder crop is in cob stage or Tussling stage, harvest it for preparation of silage. Very mature stage is not good for preparing silage as its sugar content is decreased as well as fibre percentage in increased; this kind of fodder is less suitable for silage making.
After harvesting fodder crops, let it dry for 5-6 hours in shed so that moisture content of fodder will decreases from 80% to 65-70%.Care to be taken to avoid silage making in rainy days or crops containing dew drops in winter season because moisture is more in this situation so there may be chances for development of mould in silo pit during storage period. Following steps to be taken while filling silo pit-
• Prior to filling silo pit / tank, clean& dry it.
• Cover with plastic film inside pit/tank in such way that it will cover all sides of pit/tank.
• For making silage, chaffing of fodder is essential component. With the help of chaff cutter machine, make pieces of 1.5c.m. to 2 c.m. length of green maize.sorghum,sugarcane tops,marwel,Fodder bajara etc for filling silo pit.
• Prepare separate solution in 15 to 20 litres of water for Urea, Jaggary, Mineral mixture & common salt in separate pots/buckets & then spread it on layer of pressed chaffed green fodder while filling silo pit/tank.
• Start to fill chaffed green fodder in pit or tank.
• After making 4” thick layer of chaffed green fodder, press it with wooden plank(Like Mortar) in such a way that air will not entangled in chaffed fodder. Then sprinkle it with prepared solution of Jaggary, Mineral mixture, Urea, Common salt & whey.
• Follow the same procedure until filling of pit/tank 1 to 1.5 feet above the ground level(In pit).Then covet it from plastic film from all side carefully.
• Covet it with Trash, Wheat straw, Soil & dry hay to protect it from entering rain water in to it. If possible to temporary arrangement of shed above the silo pit/tank.
• It will require 45 to 60 days to make good quality of silage.
Use of silage————
After 8-10 weeks, silage is ready as feed for animals. Open pit/tank initially from one side of for use. If it is not in use, then cover it carefully with plastic film so that air will not go inside in silage. Initially fed animals with 5-6 kg silage by adding it with chaffed green fodder to develop taste to animals. Once animal likes sweet-sour taste of silage; it will eat it with good liking.
Quality of Silage————
Mould : If silage while filling pit/tank, not well pressed; there will be growth of mould.
Odour : Good quality silage has sweet & sour taste.
Colour : Good quality silage has faint green or brownish colour. Rotten silage has black colour.
pH : Good quality silage has pH of 3.5 to 4.2.
Compiled & Shared by- Team, LITD (Livestock Institute of Training & Development)
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Reference-On Request.
