11 December 1998

Drive towards sustainability

THERE will be increasing pressure on farmers to move to sustainable agriculture. That will mean more and more emphasis on farm-produced feed and plant breeders will have a major role to play in that.

The forecast came from IGERs Dai Hides at the BGS meeting. A key in the efficiency of sustainable systems is optimising the protein/ energy balance in the rumen.

"Breeders have made significant advances in improving the energy value of grasses through improved digestibility and water soluble carbohydrate content. But the BSE crisis has led to public distaste for products like fishmeal in ruminant diets and there is now an urgent need to produce more on-farm plant protein," he said.

Up to 40% of nitrogen in grass could be lost as ammonia because rumen microbes could not capture the non-protein nitrogen. Provid-ing extra energy in the grass could help, as could breeding grasses with improved enzyme activity.

An example is a mutant gene transferred from a wild fescue to perennial ryegrass which greatly improves digestibility of lignin in the plant. The same ryegrass also contains high levels of unsaturated fatty acids. It was possible to select for linoleac acid which could reduce blood cholesterol through incorporation into ruminant products. &#42