8 March 2002

Crimping additive doubts

By Richard Allison

DESPITE considerable producer interest in crimped feeds, there is conflicting advice over which additive to use to ensure successful storage, making independent testing a priority.

Many crops can be successfully crimped and ensiled, including cereals from wheat to grain maize, and protein crops – such as peas, beans and lupins, says CEDAR director David Beever.

"Once the moisture content of grain is down to 35-40%, its nutritive value is unlikely to rise with further drying. This questions the effort of drying the crop before storage, only to put it in a ration and wet it again."

Other advantages of crimping include less grain loss due to shedding and a wider harvest window, says SAC beef specialist Basil Lowman. "The straw has a higher nutritive value, which can be dried and baled conventionally or preserved moist using a suitable preservative to prevent spoilage."

While reviewing existing research, Prof Beever has raised several questions on the suitability of some types of additives being marketed for crimped feeds. "While it is possible to ensile crimped cereals without an additive, clamp losses can be high and aerobic stability is poor. Such spoilage results in feed with reduced nutritional value and palatability."

An effective additive appears to be a small price to pay to ensure quality feed, says CEDAR researcher Sarah Harrison. "The feeding value of crimped cereals and proteins is too high to risk such losses."

This is why care is needed when selecting an additive for use on crimped feeds, says Prof Beever. "There are two main types of additive for use on ensiled grains, acids and biological inoculants. Some blends of organic acids and acid salts have been shown to work well, ensuring a good fermentation and a stable product at feed-out."

With recent advances, it is now possible to remove most corrosive properties of acid products, making them little more than mild irritants. But it is worth checking the level of active ingredients in such products, some can have higher water contents than others," he warns.

"Some commercially available inoculants are based on Lactobacillus buchneri, which modifies fermentation to produce a range of end products, including lactic acid, acetic and propionic acids and mannitol. These are believed to inhibit growth of yeasts and moulds and help reduce aerobic spoilage.

But the inoculant must contain sufficient viable bacteria, says Dr Harrison. "This ensures the bacteria dominate fermentation and achieve the desired reduction in pH. However, Dutch research suggests that clamp losses can be higher when using this type of inoculant, compared with no treatment."

She stresses that inoculant use on crimped feeds is under evaluated. "Most work has been done on maize silage, so their effectiveness on crimped cereals and pulses is unknown."

But its not the type of additive thats important, its good clamp management, believes Dr Lowman. "Thorough consolidation of crimped material grain and effective sealing of the clamp are essential, together with using a narrow clamp.

"Apply extra additive, with a watering can, to the clamps top and sides. This also helps seal the sheet down. You could use a vacuum tanker to suck out excess air and sheet well to maintain the seal," he adds.

One concern when feeding acid-treated cereals is excess acid loading on the rumen, explains Dr Harrison. "But a typical cow produces 7kg a day of acid from rumen fermentation of feed. Feeding about 5kg a day of crimped wheat treated with acid will increase this load by 45g a day, which is less than 1% of total acids in the rumen."

Crimped cereals and dried cereals from the same crop may have different feeding characteristics, says Prof Beever. "Crimped cereals have not been fully evaluated in the UK, but early work at CEDAR suggests there may be important differences in the way they are digested in the rumen which require further investigation."

For beef cattle, Dr Lowman says crimped cereals can replace dry grains on a 1:1 basis. "Crimped cereals tend to be safer to feed than dried grains, in terms of the risk of acidosis," he adds. &#42