Page 125 - Agriculture_Form_Three

Agriculture for Secondary Schools

Silage making: This involves keeping of chopped succulent fodder or forage in a
suitable air-tight container (silo) so as to undergo mainly lactic acid fermentation
with the aim of storing. Silage making is the preservation of a forage (or crop residue
or by-product) based on a lactic acid fermentation under anaerobic conditions.
The lactic acid bacteria ferment the plant sugars in the crop into lactic acid. The
production of lactic acid reduces the pH of the ensiled forage which inhibits spoilage
by microorganisms. The forage preserved in this way is termed as silage. Silage is
preferably made from pastures that are harvested before they are fully matured. In
cereal forages, this stage is commonly referred to as the milk-stage. At this stage,
such forages or pastures are most nutritious. Silage is very palatable to livestock and
can be fed at any time. However, if made under inappropriate conditions, poorer
quality fermentations can occur, producing other acids such as butyric acid instead
of lactic acid. This results in unpleasant, unpalatable and lower quality silage. It
must be emphasised that air is the biggest enemy of silage.

Silage making is long practised by larger agricultural sectors where production
methods rely on heavy equipment and large production. A heavy equipment
is employed to dig or build storage pits and compress the forages. This makes
silage making appear to be far from the reach of smallholder farmers. However,
smallholder farmers can make their own silage depending on the size of operation
but the principles of silage making are the same. The major difference is the type
and size of storage used. The success or failure in making quality silage is greatly
affected by procedures followed and the set of guidelines.

Procedures of making silage: There are five basic steps in silage making. These
are harvesting of forage, wilting or addition of fermentable substrate to the forage,
chopping the forage into small pieces, filling the silo and compacting the forage, as
well as sealing of the silo, storage and feed out.

(a) Harvesting of forage
Forages should be harvested when there is excess to feed requirements and when
they are high in quality. If a forage harvester is available, the forages should be
cut using the harvester. Forages harvested for silage should be at the same stage of
maturity as if feeding fresh. Fodder may be harvested by hand tools (e.g., sickle and
machetes) or by machines (e.g., tractor powered forage harvester).

(b) Wilting of the forage or addition of fermentable substrate
The harvested material should be left in the field to wilt so as to raise the dry matter
content to between 30 - 35%. Wilting will enable the cut forage to undergo more
satisfactory fermentation. Wilting involves laying the cut forage on racks or against
walls so as to allow the sun’s heat to evaporate some moisture from the plants. If
rain is likely to fall, the material must then be covered with water proof cover like
plastic or moved under shelter.

Student’s Book Form Three
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