Kalungu farmers appreciate benefits of potato vine silage
A group of farmers in Kalungu District prepare, mix and store silage from sweet potato vines and roots. File photo
Dairy farmers in Kalungu District have begun to appreciate the economic benefits of silage made from sweet potato vines. This follows training they received from Bavubuka Twekembe, a youth group based in Seguku Village, Makindye Sub-county, in Wakiso District.
The group spent some days with members of Abenda Emu Farmers Group in Kalungu District to train them in making silage. They also provided them with the forage chopper.
Increased yields
One of the members, Praxeda Nakakande from Buyikuzi village, in Bukulula Sub-county, explains that members bring the potato vines to be chopped and return to their homes where they make the silage. We have all noticed increased milk yields.
“It is also cheap since we grow the potatoes and have fairly easy access to maize bran, which is a key ingredient. The silage is also good for pigs,” she says.
The Bavubuka Twekembe group was itself trained in silage making by Dr Jolly Kabirizi, a forage scientist at National Agricultural Research Organisation (Naro).
Acquire skills
Having mastered the skills, the youth now prepare silage for sale to the farmers especially during dry periods when fodder is scarce.
“It is an income-generating opportunity for youth who cannot practice agriculture as a direct employment option,” says Dr Kabirizi, adding that they also undertake to train farmers groups in making the feed and other skills related to livestock nutrition.
Sweet potato is the third most grown food crop in Uganda after bananas and cassava. This is in addition to the country being an important sweet potato producer in Africa.
But the farmers have not been taking due advantage of its non-human food value (vines and roots), which have often been left in the field.
Of the total, more than 30 per cent of the roots and vines produced annually are left in the field where they dry up and lose their feeding value as fodder.
Good feed
The Bavubuka Twekembe buy the vines from farmers or markets to turn them into silage which they sell to pig and dairy farmers.
“Silage making is an easy and affordable technology that can be used to conserve sweet potato roots and vines for feeding livestock in times of shortage,” notes Dr Kabirizi.
“It is produced by controlled fermentation of a crop of high moisture content such as sweet potato vine and roots, elephant grass or maize harvested at milking stage (when the cobs have just formed).
Lactic acid is produced when sugars in the crop are fermented by bacteria in a sealed container (silo) with no air. The silage is good feed for pigs, goats, sheep, cattle, donkeys, horses and rabbits.”
Excellent complement
Silage making ensures off-season availability of feed for at least three months from materials, which would otherwise go to waste due to high moisture content.
Ensiling removes the risk of toxic substances and harmful micro-organisms besides enhancing the palatability of the feeds.
Kabirizi discloses that silage from sweet potato vines has high protein content and digestibility, which makes it an excellent complement to grass feeds.
Cost-effective
Sweet potato roots provide a good amount of vital minerals such as iron, calcium, magnesium, manganese, and potassium that are essential for enzyme, protein, and carbohydrate metabolism.
“Silage making ensures more economical use of plants with high yield of green mass,” she says.
The use of fermented silage for feeding animals has been proven to be cost-effective and nutritious.
Improve production
This is why Naro and its National Livestock Resources Research Institute (NaLIRRI), International Potato Centre (CIP) plus International Livestock Research Institute (ILRI) are developing and promoting appropriate technologies such as silage making to help farmers improve production. It is with support from European Union and International Fund for Agricultural Development.
In line with this, NaLIRRI has developed a “Sweet Potato Vine-Based Partial Milk Substitute” which can be used as a substitute to milk. The objective is to reduce the cost of rearing a calf without adversely affecting its health and yet save more milk for consumption, processing, and marketing.
The bull-calves can therefore be raised with minimum resource input to add to the financial benefit of farmers under intensive (zero grazing) dairy systems.
How to make silage and the advantages as an animal feed
After harvest the sweet potato vines, transport the material to where silage making is to take place and leave it to wilt for a day to reduce moisture content. Material with high moisture content tends to decompose very fast.
Chop the vines and roots into pieces of about 1-3 cm long before ensiling. Chopping can be done manually but this takes a lot of time and is labour intensive. So, it is preferable to use a motorised forage chopper.
Weight the chopped material before adding such ingredients as molasses, treated poultry litter, wheat or maize bran. Ideally one kilo of maize bran should be added to 10 kilos of maize bran. Then, one part of molasses is mixed with two parts of water (that is, one cup of molasses with two cups of water) to make it easier to apply molasses to the chopped material.
Sprinkle the diluted molasses (preferably in a watering can) or the bran onto the chopped material as evenly as possible. Turn/mix the material repeatedly to ensure an even spread. Maize bran produces better silage than molasses mixed with water. Tie one end of 1.5m long plastic tubing with a piece of a sisal string to make a large “plastic bag”.
Place about 50 kg of material already mixed with molasses or bran into the “plastic bag” and compact as much as possible. Tie the top of the “plastic bag” tightly to ensure no air remains in the ensiled material.
Store the bags away from other feed sources to reduce damage from birds and rodents. Sweet potato vines and roots silage can be kept for more than two years as long as air is kept out completely. Ensiling provides clean silage.
According to Dr Jolly Kabirizi, a forage scientist at Naro, sweet potato vines fermented with treated chicken manure result in higher crude protein content than the other silages. SThe residues include sweet potato vines, any sweet potato roots rejected by the farmer as unsuitable for human consumption and the peelings.
She says the silage should be fed for at least one month after it has matured. “After feeding, the feed troughs must be cleaned out to prevent any remaining silage, which gets spoiled, contaminating the next feed out.”
Silage can be provided in a number of different recipes based on its composition and the breed and use of the animals. In general, silage should be used up to 20 kilograms per day for a 550-kilogramme animal and up to four kilogrammes per day for small animals like pigs, sheep and goats.
To avoid off-flavours in milk, silage should not be fed to lactating cows before or at milking time. It is more economical to feed silage as a supplement to other diets such as hay or grass.
Well-made sweet potato silage is a wholesome and nutritious feed for all classes of livestock. Use of sweet potato silage can significantly increase milk yield and meat by 15-20 per cent.
Well-prepared sweet potato silage can be described as having a smell similar to fermented milk and a firm texture. Poor quality silage tends to have a smell like rancid butter or ammonia.
When feeding, open the bag and after removing the amount needed, tie it again without trapping air inside.
