A maceration treatment of leucaena foliage improves its nutritional value by reducing mimosine concentration

Giant leucaena produces high dry matter yields but the foliage contains mimosine, a non-protein amino acid that is toxic to animals, especially non-ruminants. Reducing mimosine concentration in foliage following harvesting may allow for greater use of Giant leucaena and mitigate the negative aspects of higher mimosine concentration in some varieties. We  evaluated two methods for post-harvest treatment of foliage of a highly productive interspecific hybrid variety ‘KX2’ for reducing mimosine concentration: (i) maceration treatment; and (ii) extraction with 0.1 N HCl. Mimosine as a percentage of leaf dry matter ranged from less than 1% DM to around 3% DM. Although both methods reduced mimosine concentration, extraction by 0.1 N HCl also reduced gross energy, protein and carbohydrate concentrations of leucaena foliage. The maceration treatment, on the other hand, caused little reduction in crude protein and crude fat concentrations but markedly increased the carbohydrate concentration. ADF and NDF concentrations were also reduced as a result of maceration treatment. The estimated gross energy concentration in macerated foliage was not significantly lower than in unprocessed foliage. A suitable mechanical method for post-harvest maceration of leucaena foliage, e.g. a wood-chipping machine, could be used to reduce mimosine concentration in the foliage, making it safer for feeding to livestock and enhancing the feed value, especially for non-ruminants. These methods should be tested by conducting feeding studies to determine the possible benefits in animal performance from feeding macerated foliage.