Leucaena contains large amounts of mimosine (up to 12% DM in young shoots), a toxic amino acid that is detrimental to non-ruminants (horses, donkeys, pigs and poultry). In ruminants, mimosine is broken down in the rumen to DHP (3,4 and 2,3 dihydroxy-piridine), a goitrogen that is detoxified by rumen bacteria. However, mimosine causes Leucaena to be toxic to cattle if fed in large amounts (more than 30% of the diet) over long periods. It induces low feed intake, and reduces live-weight gain and reproductive performance. Toxicity symptoms are alopecia, excessive salivation and enlarged thyroid glands (Norton, 1998).
Supplementation with zinc sulphate or Fe salts alleviates leucaena toxicity. Mimosine content can also be reduced by soaking in water and drying. Another way to detoxify mimosine is to transfer rumen degrading bacteria (Synergistes jonesii) from adapted cattle, sheep or goats to non adapted ones (Norton, 1998).