When you harvest fodder, you may feed it directly to your livestock. You may also store some to feed the livestock for the next one or two days. But what if you want to feed the fodder a year or two from the harvest date?
Making silage will allow you to preserve the fodder for such a period while maintaining a large percentage of the nutritional value. Further, it allows you to store excess fodder and use it to feed livestock when there is a shortage, particularly during the dry season.
What is Silage?
Silage refers to preserved pasture. It involves chopping high-moisture fodder and subjecting it to anaerobic respiration. In short, the fodder undergoes controlled fermentation in the absence of oxygen. The anaerobic conditions allow the lactic acid-producing bacteria to ferment the sugar in the fodder and release lactic acid. This acid causes the PH of the fodder to drop. When the reaches around 4-5, the sugar breakdown seizes, and the fodder remains preserved until the silage is opened and exposed to oxygen.
The PH of the mixture must drop (the mixture must become more acidic), otherwise, a low PH leads to the fermentation of the silage by bacteria different from the lactic acid-producing bacteria. Consequently, your preserved fodder will contain by-products such as ammonia that taste bad to the livestock. That is why you must do everything possible to promote anaerobic fermentation during your silage making process.
There are several types of fodder silos including bunker, polytube (bag), tower, pit(trench) silos, etc. We have crafted a piece discussing the steps of making trench (pit) silage in Kenya.
Select the Forage Crop You Intend to Use
The first step in the silage-making process in Kenya is deciding the fodder crop to use. Consider varieties of crops that take a short period to grow and can be produced multiple times. Some of the best crops include maize, grass, sorghum, millet, oats, and Pakchong-1 Napier grass, etc.
Prepare the Pit
Here is how you prepare a silage pit:
- Dig the Pit
Choose a safe and dry place to dig a pit. A slightly sloping ground is preferable. The pit should be deeper on the higher side of the sloping ground and shallower on the lower side to form a wedge-like shape. The amount of fodder to be preserved determines the size and dimension of the pit.
- Cover the Pit
Use a polythene sheet to cover the bottom and the sides of the pit. The sheet prevents the forage from contacting the soil. Contaminating the forage with soil may negatively affect the preservation.
Prepare Your Fodder
Below are the steps for preparing your fodder for silage:
- Harvest the Fodder
Harvest the forage when it contains the highest amount of nutrients. Pastures have the highest nutrient levels just before they mature. As the crop matures, the leafy content decreases while some parts of the plant e.g., the stem become harder. Further, a fully mature forage will have a higher amount of fiber which is less palatable, less digestible, and has a reduced protein content level.
- Wilt the Fodder
Wilting is crucial during the silage-making process. It helps increase the Dry Matter (DM) percentage and reduces the quantity of effluent produced. The sugars within the forage are water soluble, thus precious energy inside the silage will get lost in the flow of effluent if the plants have high moisture content. Further, wilting leads to an increased sugar concentration thus making the resulting silage stable at a higher PH. Therefore, less lactic acid will be needed to preserve the fodder.
One way to wilt your forage is by cutting the crop when the dew has evaporated and collecting it later the same day. Another method involves harvesting the crop in the afternoon and wilting it for 24 hours. Some farmers lay the crops against a wall or place them on racks. Spreading or turning the forage is crucial to reduce the wilting time. However, monitor the dry matter content of the forage to avoid drying the crop excessively which may negatively affect the anaerobic stability of the silage at feed-out. The ideal Dry Matter content is between 28 and 32%.
- Chop the Fodder
After wilting the forage, chop the green into small pieces. The desirable chop length is 2-4cm. Too long pieces make it harder to squeeze all the air out of the spaces between the forage, particularly at higher dry matters. However, shorter lengths may not stimulate the cow’s rumen activity sufficiently.
Smallholder farmers can use knives and achieve similar chop lengths. Unfortunately, the manual process is laborious and time-consuming. Using a mechanic forage chopper e.g., a chaff cutter helps chop quickly at required lengths. Regardless of the chopping method, ensure your cutting blade is sharp.
Fill the Pit with Fodder
Farmers in Kenya have their different ways of completing this silage-making stage. For instance, some farmers add molasses to the fodder while others do not. Further, farmers have different heights at which they add fodder before compacting. Some farmers will add forage to the pit up to about 75cm and compress it to about 30cm. They will then refill the pit with the remaining pieces of fodder and compress again. Other farmers will compact the silo after adding forage every 15cm until the silo is filled. The bottom line is ensuring a thorough compaction to expel as much air as possible.
One way of compacting the fodder involves rolling a tightly closed drum filled with water. Tractors are ideal for trampling large silage pits. Some farmers in Kenya also leave a space (around 1m) on one side of the pit to allow monitoring of the silage. If you use molasses, you can mix it with water in a ratio of 1:3 and sprinkle the solution on top of the forage before every compaction. Molasses provide readily available energy and minerals to favour the development of the bacteria that aid in decomposition. It also improves the smell and taste of the silage.
After the final pressing, you cover the pit with a polythene sheet to avoid water seepage into the silo. You will need to add soil on top of the covering sheet to keep the air out. The soil also protects the polythene cover from damage by rodents. Further, dig a small trench around the sides of the pit to prevent water from seeping into the silo.
Allow Fermentation
Keep checking the silo for damage and heating. You will be inspecting the polythene for tears or holes which could be caused by rodents. Ensure the edges and seams remain weighted down.
You also need to check the temperatures. Too high temperatures in the first four days would mean one of the silage-making steps was done incorrectly. It could mean the compacting was inadequate, the fodder was too mature or too long or the forage had too low moisture content. High temperatures result in a dark brown or black silage. Moderate temperature yields brownish or yellowish-green silage due to the action of organic acids in chlorophyll and its conversion into phaeophytin (a brown magnesium-free pigment).
You will need to wait for the fermentation to occur before you can use the fodder. Generally, silage is ready at least three weeks after preparation. However, the optimum fermentation takes 60-70 days. A good-quality silage will have an acidic taste and smell. It is also free from butyric acid.
Use the Silage
When the silage is ready, you can open it from the lower side of the slope, take enough amount of forage you wish to feed your livestock for that time, and cover it properly to avoid exposure to air and heating. However, you can have the pit remain intact and use your silage after a period of up to two years.
Silage allows you to preserve forage and use it to feed your livestock during periods of shortage and droughts. You can produce fodder in excess during the rainy season and preserve it to feed your flock a year or two later. Due to economic reasons, prioritize feeding your silage to top-producing animals.