28 May 1999

Extra wrap is worth the cost

USING six layers of wrap on silage bales is worth the extra expense, but developing wraps that keep more oxygen out of bales is possible after a recent IGER invention.

Speaking at Grassland 99, IGERs Raymond Jones said using six layers of wrap could halve the flow of oxygen penetrating film compared with four layers. Oxygen increased the micro-organisms, micro-toxins and heat produced in the bale, he said.

While the extra two layers increases the wrap costs by 40p to about £1.40 a bale, it is worthwhile because it cuts silage losses and raises its nutritive value. But that is only when high quality material is put into bales, he added.

It has only recently become possible to measure oxygen flowing through silage wrap. This is because IGER has developed and adapted a small micro-electrode that can measure oxygen in legume plant roots. These were built into a cell that measures oxygen diffusion through silage wrap film, said Mr Jones.

"Now film manufacturers can develop new films to improve silage quality. This will take us to a new generation of films."