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Forage & Nutrition
Guide 2018
Topical tips for better quality
One of the key measures of efficiency and sustainability is the extent to which
you are maximising the use of home-grown forage and silage in the winter
diet of livestock. There are a number of ways to achieve this
Ensure you produce enough silage to feed your livestock
through the winter, however long that may be;
Maximise the quality of the silage you produce so your
livestock can rely less on bought-in feed; and
Minimise waste and secondary fermentation.
To achieve these requires you to grow good grass to start with
and minimise the losses in dry matter (DM) and nutrients that
occur during the conversion and storage processes.
Safeguarding both quantity and quality starts as soon as
your grass is cut. You need to minimise those losses. It might
be tempting to cut grass later in the hope of getting more
yield, but the problem is that once cutting gets too late, grass
quality in terms of protein, digestibility and metabolisable
energy all decline. As an example, after heading, the
digestibility of grass falls by about 0.5 per cent a day. For good
quality silage at an acceptable yield, consider cutting just
before heading. Although it might be tempting to use a low
cutting height to get more yield, lower cutting will give a lower
quality silage.
In addition, dead plant material in the base of the sward
contains higher levels of undesirable micro-organisms that
can hinder fermentation and increase aerobic spoilage
(heating of the silage).
Cutting too low also increases the risk of introducing
undesirable soil micro-organisms, such as clostridia into
silage, increasing the risk of a poor fermentation, reducing
its feed value, or even potentially contaminating the silage
with listeria. Effective wilting increases the percentage DM of
the grass and reduces losses from effluent. It also means the
silage will stabilise at a higher pH. A higher DM will also inhibit
undesirable clostridia bacteria.
Unfortunately, as soon as grass is cut, sugar levels start to
decline because they are being used up by the plant, since
it is still living, and by any undesirable bacteria that may
Author: Noel McGrath
Forage specialist, Volac Ireland