There are largely three magic components of a successful zero-grazing dairy enterprise. One, get the right breed for milk production, two, construct a good shelter for the cow and three, make sure that the cow is well-fed.
According to experts, feeding livestock is the underlying step towards achieving better milk or body sizes.
Sweet potato is magic
According to the International Potato Centre, Uganda is the largest producer of sweet potatoes in Africa.
The sweet potato is an important crop that fits well in the country’s farming and food systems and ranks third after bananas and cassava, according to the Ministry of Agriculture, Animal Industry and Fisheries.
In some households, the sweet potato generates cash, in addition to being a food source.
Using sweet potato to make silage
According to Dr Jolly Kabirizi of Kyakuwa Farm, the sweet potato can be harvested twice a year in Uganda.
Sweet potato residues (vines and roots) are a valuable source of feeds for all classes of livestock. The vines have a higher crude protein content (about 20%) than that of napier grass (10%), maize silage (14%) and other forage grasses. Proteins help animals grow their bodies.
To minimise losses farmers often feed large quantities of roots and vines to pigs, goats and cattle during the two months after harvest, but this practice does not achieve the required growth in proportion with the large quantity of feeds used.
“Combining sweet potato residues with maize bran, molasses or chicken manure, offers an alternative solution to some of these constraints. The resultant silage (high-quality feed resource) can be stored for five months without getting spoiled if it is stored carefully in tightly packed plastic bags under air tight conditions,” Kabirizi says.
She adds that converting sweet potato residues into silage will also ensure a clean environment in market areas, where heaps of residues are usually dumped.
How to prepare silage
- Sweet potato silage can be made using chopped potato vines or combining chopped vines mixed with roots of non-commercial value (at a ratio of 70:30).
- Select a good strong plastic sheet with high density (1.5m width, gauge 600 to 800mm) to make plastic tube silage bags. High density plastic reduces the potential for tearing. Imported plastic tube silage bags are now available in Kampala. Plastic fertiliser bags make good silos. Plastic drums are expensive, but can be used for many years and are not damaged by rodents.
- After harvesting the sweet potato residues, the material is transported to where silage-making is to take place and left to wilt for one day to reduce the moisture content. Materials with high moisture content tend to rot fast.
- Chop the residues (vines and roots) into small pieces of about 1-3cm long, before ensiling. Chopping can be done by hand, but this takes a lot of time. It is preferable to use a motorised forage chopper.
- Add fermentable substrate, for example, molasses, wheat or maize bran. Molasses or maize bran serve as a preservative.
- Add one kg of maize or wheat bran to 10kg of chopped sweet potato material.
- Mix one part of molasses with water to make it easier to apply 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.
- Tie one end of a metre-long plastic tubing with a piece of a sisal string to make a large “plastic bag”.
- Silage can be kept for more than three years as long as air is completely kept out.
- Place about 50kg 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 ensuring no air remains in the ensiled material.
- Store the bags away from other feed sources to reduce damage from birds and rodents.