5 July 2002

Its not a poor mans maize

By Richard Allison

PROCESSED urea-treated whole-crop wheat is not poor mans maize in dairy rations, maintaining high milk yields and at similar cost, according to MDC funded research.

Previous work has shown that harvesting whole-crop wheat with foragers fitted with processing mills enhances its nutritive value, says Harper Adams University College researcher Liam Sinclair.

"Overall starch digestibility was increased when using the adapted forage harvester. This improved digestibility, reducing daily feed costs by 5p a cow, equivalent to £1000 for a 100-cow herd over a 200-day winter, while maintaining the same milk yield."

Knowing this, he set out to find out how processed whole-crop wheat compares with maize silage, particularly in more marginal maize growing areas where quality can be lower. "Maize silage is often viewed as a higher quality forage than whole-crop wheat," says Dr Sinclair.

To compare these two forages, 44 cows were fed 6.5kg of a standard 25% crude protein dairy concentrate, 2kg of rolled wheat and a mixture of one-third high quality grass silage and two-thirds test forage. The maize ration also had urea added to balance extra nitrogen supplied in whole-crop additive.

Cows fed processed whole-crop wheat averaged 34.4 litres a day over the 15 week period, similar to 34 litres/day for cows fed high quality maize silage. There was also no difference in milk fat or protein percent.

The costs were also similar for both forages on a £/t DM basis at a range of different dry matter yields. At a yield of 13t DM/ha, maize will cost about £38/t and whole-crop £42/t DM, including arable aid and added urea.

Maize silage used in the study was high quality with a dry matter content of 31%, more than 30% starch and a metabolisable energy content of 11.5 MJ/kg DM. Processed whole-crop wheat had 31% starch and a dry matter content of 82%, he says.

Dr Sinclair says that unless maize can be made with a dry matter and starch contents of at least 30%, cows may not perform as well. "Therefore, in areas where maize cannot be grown well, processed urea-treated whole-crop will result in yields similar to those where maize can be grown well.

"Even in good maize growing areas, whole-crop is an effective alternative with additional advantages. Whole-crop is more flexible, as the area and cutting height can be adjusted depending on first cut silage quality. When silage quality is poor, increasing cutting height provides a higher energy forage."

The study also investigated which feeds complement whole-crop. "Replacing 700g of wheat with lactose tended to increase milk volume by 1.2 litres, which was cost effective with lactose costing about £300/t and rolled wheat at £90/t."

At current wheat prices, feeding 2kg molasses instead of rolled wheat failed to increase milk yield; a response of at least 1.8 litres was needed to cover the extra cost of molasses. But feeding molasses increased dry matter intake by more than 3kg a day, compared with maize. &#42

In poor maize growing areas, processed whole-crop wheat will result in similar cow performance to high quality maize silage, says Liam Sinclair.

&#8226 Maintains high milk yields.

&#8226 Similar cost to maize.

&#8226 Feed with lactose?