Mimosa in visa Mart. (F-Mimosaceae) an alien invasive weed, which was first reported from Kerala in 1964, has emerged as a problem invasive weed adversely affecting the biodiversity and causing toxicity problems to animals. The toxic amino acid, mimosine, present in the plant is an anti nutritional factor contributing to clinical cases of toxicity in livestock. The mimosine content in M. invisa was the highest (9.2%) at active vegetative stage. Among plant parts, content was highest (10.4%) in the immature leaves. Ensiling the M. inv{w admixed with fodder grass in different proportions ranging from 10 to 90% for 60 days lowered the mimosine content by 32 to 46%.