Step 1: Understanding the Concept:
Leucaena leucocephala is a leguminous tree.
It contains a toxic compound.
Step 2: Key Formula or Approach:
No specific formula.
Need to know the toxic factors in feeds.
Step 3: Detailed Explanation:
Leucaena leucocephala contains mimosine.
Mimosine is a toxic non-protein amino acid.
It can cause hair loss and other problems.
Nitrate, oxalate, and tannin are other toxic factors in different plants.
Thus, mimosine is the toxic factor.
Step 4: Final Answer:
The toxic factor present in Leucaena leucocephala is mimosine.
Hence, the correct option is (A).