Make silage from sweet potato vines

Uganda is the most important producer of sweet potatoes in Africa and only second to China globally. However the value of sweet potato vines as feed for animals is little understood by farmers.

Sweet potato is the third major food crop after cassava and bananas. While the tubers are boiled or steamed and eaten, and they may also be used to make products such as pancakes, bread and juice, the vines are usually fed to livestock when farmers are short of feeds.

However, the farmers could not preserve the vines for use during times of fodder scarcity. For those who do not keep livestock, they often went to waste.

Most smallholder pig farmers find it hard to get good quality commercial feeds due to the relatively high cost. They feed them on whatever is available, for instance, crop residues, weeds, rotting fruits, and kitchen left-overs which often result in low quality animals.

Feeds play a key role in pig production and their cost can reduce or increase the farmers’ profit. Yet farmers’ knowledge of alternative nutritive and cheaper local feeds is quite limited.

Working among pig farmers in Masaka and Kamuli districts, the scientists found that when pigs are fed on sweet potato silage (60 per cent) and other locally available feed (40 per cent), they grow fast, gaining several kilogrammes per month.

The researchers are also training the farmers to make silage from sweet potato vines. It makes it possible for farmers to feed their animals on nutritive sweet potato vines, in silage form, to increase the weight for more profits.

People who cannot or do not keep pigs, but produce sweet potato, can make silage and sell to the pig farmers.

A youth group, Bavubuka Twekembe, has already gone into doing this and training other farmers as well.

To make silage, a farmer collects the vines and roots which are chopped with a panga or a motorised forage chopper machine. The pieces are then dried under the sun for perhaps a day. Recommended ratio is 80 per cent chopped vines and 20 per cent chopped roots.

Then, he or she adds eight to 10 kgs of maize bran to 100 kgs of the mixture (vines and roots) and quarter a kilo of salt.

With two metres of black polythene (gauge 1000), tightly tie one side so that it becomes like a bag. Place the mix into the polythene container in small quantities and compress to remove air spaces. After ties up the top side tightly ensuring there is no air getting in. If air enters, the silage will get spoiled.

The plastic bag is then placed in a safe place, free from rats, birds, and any other creatures that may perforate it to let in air.
After about 45 days, it will be ready for use as silage for pigs to eat. When opened, it must be utilised in less than 10 days.
Sweet potato silage can also be made by burying the plastic container underground for about 40 days.

How it is done

The research programme supported by CGIAR, European Union and International Fund for Agricultural Development (IFAD) was carried out by International Potato Centre (CIP), International Livestock Research Institute (ILIRI) and Naro as well as other research organisations and universities.

It proves the technical feasibility and economic viability of sweet potato silage, which pig farmers can use to improve production at a low cost.

Some, like Bavubuka Twekembe, who have been trained by Dr Jolly Kabirizi from Naro, add calliandra leaves. It has additional nutrients for making pigs grow faster.

Farmers are encouraged to grow bio-fortified sweet potatoes because of their enhanced nutrients—iron and Vitamin A.

Last month, scientists, local leaders and farmers who participated in the programme met in Masaka for the launch of the new technology.
Annette Sserabidde Zawula, Vice-chairperson of Kabugagali Twegatte Wamu Farmers Group, testified that she watched her pigs grow bigger because of feeding them with sweet potato silage.

Elizabeth Akiror from Uganda Martyrs Nkozi University researched on the best potato varieties to grow.

A sweet potato silage business centre was also set up in Masaka Municipality, where farmers will go for any assistance about the technology and to buy silage. Another centre has been set up in Kabonera Sub-county while another was opened in Kamuli District.