An amino acid and works very well as a supplement for debilitated and weak animals. This is a product that the Squirrels and More Rehab Clinic will never be without. This is a fantastic amino acid that will help your weak, debilitated animal metabolize protein, it will also help the immune system. As our label reads: " A pinch will grow an inch" and we mean it. We love this stuff! We can't recommend it enough.