Allan & Erna Penderis, Tammac Consultants cc
Stage of cutting
It is essential that the silage be cut at the right stage of growth. The critical figure is 35%
dry matter (and if you err, err on the dry side). Milk line is not a good estimate of dry
matter. To determine when the crop will be ready to ensile proceed as follows:
Chop up two typical plants (the whole plant) into pieces about eight mm square. Put
the chopped plants into a plastic bag and have a laboratory determine the dry matter
content. We suggest that you contact your concentrate supplier who is bound to
have the necessary facilities. Alternatively, use a microwave oven and scale to
determine the moisture content. (Instructions are available on request). The maize
must be ensiled at between 35 and 40% whole plant dry matter. Calculate the
optimum silage-making date by using a 0.5% per day dry-down rate. (e.g. if your
analysis is say 28% dry matter then 35-28 = 7% @ 0.5%/day = 14 days from today
when the silage should be cut). Depending on how quickly the maize can be cut and
ensiled, work out the date on which you should begin cutting to achieve an average
of between 35 and 40% dry matter.
Cut the maize plant at least 300mm (12”) from the soil surface but preferably 400 to 450
mm (18”) high.
Length of cut
If the maize cannot be processed (kernels cracked) then chop the material to an
effective chop length of about 12 mm, i.e. each piece of chopped material should be
about 12 mm wide. Processed maize can be cut to 20 to 25 mm in length. The aim is to
cut as long as possible up to 25 mm (1 inch) in length while ensuring that at least 90% of
the kernels are broken (damaged in some way) in the chopping process.
Line the sides of the silage pit with plastic sheeting, leaving sufficient to fold back over
the full pit to a distance of about one metre. Line the bottom of the pit to a depth of
about 150 mm with old hay or straw.
Spend considerable time and effort in effectively compacting the silage in the pit as it is
offloaded. When offloading, have the silage spread as thinly over the surface as
possible and have at least two tractors compacting continuously. Do not allow any
wheeled equipment to pick up soil and deposit this on the silage. If necessary, spread a
thick layer of hay/straw on the approach to the silage pit.
Close the pit with plastic sheeting after each day’s work.
Salt as surface preservative
When fully filled and compacted, spread 3kg of course salt per square metre on the
silage surface. Lightly water the salt into the silage mass.
Sealing the pit
Fold the plastic sheeting covering the edges of the pit over the silage surface and then
cover the silage pit with plastic sheeting from front to back. Ensure that rain run-off
cannot seep into the silage by making the necessary soil diversions around the pit.
Place a layer of old hay or soft straw onto the plastic sheeting to a depth of about 100
mm. Place old motorcar tyres onto the hay covering so that all tyres are touching – you
will need a lot of tyres to do this job effectively.
Ready to use
The silage is ready to be used after 28 days. When feeding silage, remove the silage
from the pit face by cutting a vertical face into the pit. Keep this loading face smooth and
neat. Only roll back the silage sheeting as far as necessary to expose the amount to be
cut each day.
A Holstein cow cannot be expected to consume more that about 30 to 35 kilograms of
silage per day. Maize silage is relatively high in energy but lacking in protein. This
means that protein must be supplemented in one form or another when silage is fed –
the more silage that is fed, the more protein will need to be added to the cows diet.