9 November 2001

Good management preserves benefits of whole-crop silage

By Simon Wragg

MORE livestock farms have made whole-crop silage than in previous years, but these forages are unlikely to deliver the performance many expect unless diets are balanced.

Independent nutrition consultant Hefin Richards says many producers made fermented whole-crop silage either as a planned addition to forage stocks or in response to disappointing grass yields earlier this year.

In the west of England and Wales, contractors have reported a sharp rise in whole-crop area cut this summer as a direct response to forage shortfalls and lower than anticipated grain prices.

"The whole forage situation has been exacerbated by high numbers of stock being carried by farms throughout the year, as a consequence of the foot-and-mouth crisis.

"As a result, many units face feeding fermented whole-crop cereals for the first time this winter.

"Pay close attention to managing this forage or it will not generate the results many are seeking."

As a high dry matter forage, aerobic deterioration remains a concern. Clamp management must be thorough to minimise waste once the store has been opened.

"Where possible, use a shear-grab to take whole-crop from the clamp and keep the face neat. Using an additive during harvesting will not overcome poor clamp management.

"The same is true of feed troughs and bunkers. Aim to keep feed offered to livestock fresh. Remove any heated material to protect appetite and maximise intake."

Like maize, fermented whole-crop is a mix of starch and fibre. It has potential to be a good source of fermentable energy for rumen bugs, but must be balanced with a suitable protein supply, he says (see table).

When protein levels are out of synchrony with energy levels, milk yields will be compromised, warns Mr Richards. "Protein supplements such as rapeseed meal, soyabean meal, ground nut and brewers grains can be used to balance a ration, but watch costs.

"Protein must be thoroughly mixed into whole-crop to present the rumen with a synchronised supply of energy and protein.

"It can take the rumen three weeks to adapt to a new feed, so introduce whole-crop gradually."

Feeding a high protein supplement at milking will lead to peaks and troughs in the daily supply of nutrients to rumen bugs and will not take into account different forage intakes of individual cows, he warns.

"Feed grade urea can be used at low levels in well-balanced mixed rations and urea-based liquids, pot ale syrup and condensed corn steep liquor boost protein content when mixed with whole-crop."

Minerals must also be considered. Whole-crop is low in calcium compared with grass silage. "But it is still possible to use a standard mineral mix by adding lime-stone flour to lift diet calcium content. Alternatively, a maize-balancing type of mineral may be considered when high levels of whole-crop are fed."

Depending on chop length, the forage may also need supplementing with fibre – such as chopped straw – to avoid acidosis, he adds.

Some producers may intend to use whole-crop before maize in rations. But the forage is as good as maize at buffering spring grass, says Mr Richards.

"Where units plan an early turnout and clamp management is good, it may pay to use grass silage early and save some whole-crop for spring. Being a low protein, dry, fibrous forage it complements high quality spring grazing and – used with a suitable concentrate – can act as a magnesium carrier."

FEEDING WHOLE-CROP

&#8226 Keep clamp face neat.

&#8226 Introduce gradually.

&#8226 Supplement correctly.

Typical ration for 6000-

7000-litre herd with

minimal in-parlour feeding

Feed Freshweight Dry matter (kg) (kg)

Grass silage 24 7.2

Fermented whole-crop 12 4.8

Brewers grains 6 1.5

Blend* 5 4.4

Dairy minerals 0.15 0.15

Limestone flour 0.07 0.07

*Containing equal parts of rolled barley, sugar beet pulp, rapemeal and soya.