7 July 1995

Anti-spoilage additives could be waste of cash

By Sue Rider

FORAGE maize growers who use biological or enzyme additives to stop silage heating and spoiling when it is exposed to air could be wasting their money.

That was the message of Dr Raymond Jones, head of silage evaluation at the Institute of Grassland and Environmental Research, Aberystwyth, speaking at a conference organised by Shropshire-based silage additive company Thomas and Fontaine.

He cautioned that silage dry matter losses of 25% were costing UK farmers £120m a year.

Although aerobic deterioration could occur in most ensiled crops, Dr Jones said the high carbohydrate content of maize silage made this forage the most prone to deterioration. He cited yeasts and moulds as the main troublemakers.

He questioned claims that the organic acids produced by biological and enzyme additives couldinhibit these yeasts and moulds. Research has examined biological, enzyme and acid additives in reducing spoilage in maize silage.

Biologicals tested offered little control over pH and temperature when silage was exposed to air and improved stability of the silage by just three hours compared with the control. The acid additive (MaxMais) doubled silage stability but had little effect on yeast growth. Enzyme additives made silage less stable than the control but helped reduce yeast growth.

Dr Jones also cited Canadian research which had shown the preservative sodium bi-sulphite to be more effective than biologicals at reducing silage dry matter losses. It also reduced mycotoxin-producing moulds. "The bi-sulphite knocks out the yeast population without harming fermentation."

Thomas and Fontaine claims its bi-sulphite-based preservative Regulator halved aerobic spoilage in maize silage trials at the Centre of Dairy Research.

Dr Raymond Jones questions whether biological or enzyme additives can prevent aerobic spoilage.