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Whole-Crop Cereal Silage

There is growing interest in forage cereals in the pursuit of increasing the amount of home-grown forage.

By Department of Primary Industries - 16th October 2006 - Back to News

These can provide one or two grazings (wheat, barley, triticale) or more (forage oats) and then be closed for harvest as whole-crop cereal silage, grain or preserved as an ammoniated crop, often referred to as alkalage.

This article provides information and guidance on what is currently available regarding when and how to make whole-crop cereal silage. Research is ongoing into various species and cultivars, optimum growth stage to ensile, animal performance from these, etc.

Whole-crop cereal silage can be cut at the flag leaf/boot or vegetative stage or soft dough or grain formation stage of growth. Once a cereal has headed, it flowers and then starts to form the grain. Internally, the grain goes through a clear liquid phase, followed by a milky, soft dough, hard dough and hard grain phases, the latter being harvested for flour production or feed grain. The grain in the soft dough stage will be pliant and is similar to squeezing a soft Brie cheese, usually returning to its original shape after a gentle squeeze between the fingernails. Each of the recommended growth stages has its own pros and cons.

Flag leaf/boot stage: At this growth stage the crop will be at its highest nutritive value but much lower yield than if cut at the soft dough stage. The standing crop at the flag leaf/boot stage will have dry matter (DM) of about 12 – 22% DM and will require wilting to about 33 – 40% dry matter before harvesting as bulk chopped silage, or about 38 – 50% DM as baled silage. If harvested under the above lower limits, a poorer fermentation will occur resulting in losses of DM and nutritive value, and a silage of low palatability.

Cutting at this stage will mean harvesting early in the season for autumn or winter sown cereals when climatic conditions may not be very conducive to a fast wilt. Using a mower-conditioner with the swath boards set out wide will help increase the wilting rate. A tyned conditioner adjusted to produce an aggressive conditioning and adjusted to produce a "fluffy" wide windrow is ideal. A roller conditioner set to squash and crimp the stems, also leaving a wide windrow, will increase the speed of wilting.

Tedding straight after mowing will also assist greatly but cereal crops are usually high yielding compared to ryegrass, even at this stage, and may stress tedder equipment if forward speed is too fast. There is also the risk of tedding and raking equipment picking up soil during their operations, a situation to avoid at all times.

Soft dough stage: When cut at the soft dough stage, whole-crop silage will be lower in nutritive value but yield will be about 100 – 150% higher than at the vegetative stage. The standing crop will have dried to near its ideal DM content, 38% DM, but can be harvested in the 35 – 42% DM range as bulk silage or baled at 38 - 45% DM.

The length of period in each phase will vary depending on moisture availability, sunlight hours and temperature. Very broadly speaking, barley, being the quickest species to pass through its grain forming stages, can undergo the soft dough stage in 3 – 5 days drying at approximately 2% DM/day. The other cereals may do so over 7 – 10 days drying at only about 1% DM/day. Guidelines are currently being developed to assist farmers to recognise more accurately when to harvest forage cereals in the soft dough stage.

Forage cereals should, ideally, be harvested using a precision chop harvester to produce a very short chop material which can be compacted to exclude air and to ensure the grain heads are intermingled with the rest of the plant. The harvester, preferably, should be fitted with a direct cutting front to minimise grain loss during harvest. Mowing, then raking and harvesting can result in substantial grain loss due to these operations, thereby substantially reducing its nutritive value.

If whole-crop is baled, a chopper baler is preferable to aid compaction. Netwrap for tying instead of string is preferable to minimise damage to the plastic wrap and to leave an even surface between the bale and plastic film. The bales must have a minimum of four layers of plastic applied and should be stored on their base to maintain shape.

Source: http://gippsland.com/

Published by: news@gippsland.com