Abstract: A method of promoting weight gain in an animal by feeding the animal calcined attapulgite which reduces adverse effects of a mycotoxin present in an animal food formulation. The calcined attapulgite is obtained by heating an attapulgite clay at or above 300.degree. F. The calcined attapulgite can be fed to an animal in any form either before, after, or during intake of food by the animal. Furthermore, a mixture of calcined attapulgite and bentonite may be used, instead of calcined attapulgite itself. Also provided is an animal feed composition for promoting weight gain including calcined attapulgite. Such a composition reduces adverse effects of a mycotoxin-contaminated animal feed. The composition may further contain a bentonite clay.