Abstract

Genetic improvements in forage quality can lead to improvements in animal performance. We outline two approaches aimed at generating high quality forages that increase the energy available to the ruminant. These include the heterologous expression of fructan biosynthesis genes in the leaf to produce high molecular weight soluble carbohydrate and the modification of the expression pattern of endogenous triacylglyceride biosynthesis genes to produce triacylglycerides in the leaf. In vitro experiments demonstrated the potential of the rumen to digest fructans with either b(2-6) or b(2-1) linkages, furthermore both in vitro and in vivo experiments showed that fructan reduced the concentration of NH3 in the rumen. We discuss the advantages of raising the lipid content of forage and the ramifications of expressing triacylglcyeride biosynthesis genes in the leaf. The expression of other genes that modify the quality of the fatty acids within triacylgycerol are also discussed briefly.

NJ, Roberts, KR Hancock, and DR Woodfield

Proceedings of the New Zealand Society of Animal Production, Volume 62, Palmerston North, 278-281, 2002