8 June 2001

Use whole-crop wheat to replenish forage stocks

Cereal crops may offer an

opportunity to rebuild forage

stores depleted due to foot-

and-mouth. Richard Allison

examines whole-crop

options and alternatives to

grain where its not needed

WHOLE-CROP wheat offers an ideal chance to replenish forage stocks this season and it may be worth considering buying a standing crop from a neighbouring arable farm.

There are several whole-crop options. The simplest is fermenting wheat without additives, says Harper Adams University College researcher Liam Sinclair.

"By aiming for a dry matter of 40-45% instead of 30-35%, you will gain an additional 3.5t/ha. This extra forage yield equates to a 0.3p/litre reduction in cow feed costs without any loss in forage quality and milk output."

Problems with keeping quality have been widely reported with fermented whole-crop wheat. But John Sutton, of CEDAR, University of Reading, believes that good clamping practice, including double sheeting to ensure a good seal, will avoid rapid spoilage when feeding out.

"Urea treated whole-crop has less problems with keeping quality, but many grains are found to pass straight through the cow, resulting in reduced starch digestibility. This is due to the later harvesting date with urea treated whole-crop when the grains are harder," says Dr Sutton.

When the clamp has a large face, and spoilage is likely to be a problem, Kingshays James Hague recommends treating with 3-4% urea instead of fermenting crops using an additive. "Independent testing of whole-crop additives to combat yeast and moulds have shown the importance of selecting the right one. Some improved stability, but others made the problem worse."

Recently, there has been a move towards alkalage to maximise crop yield, says Dr Sinclair. "Alkalage is harvested with a dry matter content of 70-75% and ensiled with an additive containing urea plus an enzyme. At this high dry matter, natural enzyme activity is insufficient to breakdown the urea into ammonia, so an enzyme has to be added.

"A forage harvester fitted with a forage mill helps break up the grains to avoid the problem of them passing through the cow undigested with high dry matter whole-crop silage."

This was investigated in a recent study at Harper Adams in Shropshire, funded by the MDC and Maize Growers Association. "Overall starch digestibility increased from 81-87% to 97%, when using the adapted forage harvester. This improved digestibility, resulting in cows eating 2.5kg less forage, while maintaining the same milk yield at 30kg/day."

This reduced forage intake lowered daily feed costs by 5p/cow, equivalent to £1000 for a 100-cow herd over a 200-day winter. Dr Sinclair also says alkalage has the advantage of a wider harvest window than fermented whole-crop.

"For all whole-crop options, it is important to consider cereal variety when buying a standing crop. Research at Harper Adams used Equinox and Savannah for their larger grain size. Other varieties may offer higher yields so reducing cost/t."

Milk yield can be disappointing when feeding whole-crop, due to the high straw content, says Mr Hague. "Straw content can be reduced by lifting the cutting height or choosing shorter-strawed varieties."

But recent work at Harper Adams found that lifting the cutting height from 18cm to 37cm (7in to 15in) reduced milk fat content by 0.5%, adds Dr Sinclair. "This was due to the starch content of silage increasing from 36% to 42% and NDF falling to 34% when reducing straw length."

But before deciding to make whole-crop Mr Hague advises considering what other ingredients are in the ration and whether whole-crop will fit in. "Successful feeding of whole-crop wheat requires more care than maize to avoid any drop in performance.

"Also consider rats, as they are a huge problem with both crimped and whole-crop wheat. They like the grains and find it relatively easy to burrow into the clamp, if you have a rat problem, stick with grass silage," says Mr Hague. &#42

WHOLE-CROP WHEAT

&#8226 Fermented option simplest.

&#8226 Urea improves keeping quality.

&#8226 Consider forage mill.

&#8226 Prone to rat damage.