Do Queensland cattle possess rumen bacteria capable of degrading Leucaena toxins?

Abstract

Leucaena leucocephala is a leguminous fodder tree used by northern Australian producers to provide protein and boost the weight gains of extensively grazing cattle. There is a range of commercial Leucaena cultivars available which all contain a toxic non-protein amino acid, mimosine. Many rumen bacteria can degrade mimosine to 3,4-dihydroxypyridine (3,4-DHP), which is also toxic to cattle. To enable cattle to safely gain the full benefits of Leucaena, a bacterium, Synergistes jonesii, was isolated that could degrade the toxic metabolites 3,4 DHP and 2,3-hydroxypyridine (2,3-DHP) (Allison et al. 1992). A fermenter-grown mixed bacterial inoculum, containing S. jonesii, has been produced by DAF for over 20 years as an oral drench for cattle to prevent Leucaena toxicity and maximise weight gains (Klieve et al. 2002).