FARMERS have been warned grass silage could be costing much more than they think.

An analysis of farm costings has shown third and fourth cut silage can be twice as expensive to produce as first cut.

Dr Michael Marsden, KW Alternative Feeds technical manager, believes farmers should rethink their forage strategies, consider reducing the number of cuts made, and concentrate on choosing the best value alternative forages, dry feeds and moist concentrates available.

He said the analysis of farm costings had been updated to include recent fuel and fertiliser price changes, plus clamp and feeding losses.

They show the energy needed to produce a litre of milk (5MJ ME/litre) is costing about 3.4p, 4.2p, 4.9p and 6.6p, for each of the four cuts.

In comparison, alternatives such as maize and whole crop cereal silages, plus many moist and dry co-products, typically cost less than 4p per litre.

Dr Marsden said lower yields for the later cuts of grass silage made them relatively uneconomic compared to either the earlier cuts, or maize and whole crop silages.

He said: "What is surprising is the scale of the differences, to the point where fourth cut silage is typically costing twice as much as first cut on a dry matter basis, and it's unlikely that many farms really appreciate this additional cost."

Dr Marsden recommends farmers produce forages as a source of energy and structure in the diet, since the growing number of moist and dry protein co-products from bio-ethanol production are likely to keep the cost of protein relatively low compared to energy.

Fewer silage cuts will also allow each to be made slightly later for a larger yield, even lower cost and more "rumen-friendly" fibre.