22 November 1996


The UKASTA Forage Additives Approval Scheme has been strengthened this year thanks to product monitoring. Allan Wright reports

ONLY two-thirds of the 110 silage additives on the market have official approval that they live up to the claims made for them.

The man who heads the forage additive approval scheme says that most of those which have not qualified will disappear from product lists this year.

"When the scheme was introduced in 1994, firms were given two years to provide trials data for assessment. Those which have not done so by now are unlikely to do so now and will disappear," says John Weddell from the Scottish Agricultural College.

He remembers 20 years of silage additive trials.

"It began with Add F and grew from that. We used to publish a technical note and list all the products. Then we launched an assessment scheme in the late 80s and invited firms to submit assess-ment data," says Mr Weddell.

"We were doing that in conjunction with ADAS and DANI and it worked quite successfully. The trouble was that the results were fed exclusively to advisers from the three organisations and not directly to farmers.

"The industry, led by UKASTA, saw the need for some regulation and that government would impose a system unless a trade one was available. We collaborated with UKASTA and the advisory service system was put on an official footing."

That led to the Forage Additive Approval Scheme which is administered by UKASTA, with data assessments spread between SAC (inoculants), DANI (acids), and ADAS (enzymes, absorbents, and sugars). Mr Weddell remains in overall charge of assessments to ensure uniformity.

Strengthening the scheme this year, ADAS has organised random product analysis (see pS25).

"That should give the farmer even more confidence in the scheme. If the product carries the approved logo, it means that it contains what the label says and that it lives up to advertising claims."

Approval in one or more of three categories and nine sub-sections comes after careful assessment of trials data put forward by companies.

"We allow them to put forward in-house data but find that most results are from independent trials," says Mr Weddell.

No product has nine stars against its name in the 1995/96 list but there are one or two sevens and several sixes.

The top category is approval for improving liveweight gain or milk output (A 1 and 2). The B approval covers animal feed effects – improved intake, digestibility, or efficiency of energy or protein utilisation (B 1-3). Those which benefit the ensiling process by improved fermentation, aerobic stability, reduced effluent, or reduced losses, win C 1 to 4 approval.

For an additive to be approved in a particular category, it must, for a set number of experiments, produce a significant improvement compared with non-treated silage.

Most successes have been achieved for improved fermentation (57%), intake (42%), liveweight gain (43%) and milk production (32%). At the other end of the scale, effluent limitation and reduced losses have been difficult to measure, with only 3% and 9%, respectively, of products winning approval.

Mr Weddell says that no additive corrects poor silage making management.

"But the better additive, at £1.50-£2/t ensiled, does give value for money. An animal response of 0.4 litres of milk a kg of meat will cover the cost. Such gains have been achieved regularly in college trials," says Mr Weddell.n

SACs John Weddell: "No additive corrects poor silage making management."