ED: I am not sure what this is. I am pretty sure it isn't the same as the current tiger's milk, which has multiple definitions. One of them is a nutrition bar, which was around in the 1960s, but I can not find anything talking about it. 
Okay, finally found the answer: "It was a protein drink mix that you could add orange juice or milk to." No one seems to know what to substitute for it.

Cream butter, sugars, egg and orange peel together until fluffy.
Re-sift flour with tiger's milk, baking powder, salt and spices.
Blend into creamed mixture.
Add oats, coconut, carrot and dates and blend.
Chill dough about 1/2 hour.
Drop by tablespoon onto greased baking sheets.
Bake at 375° for 15 minutes.
Remove to wire racks to cool.
Frost with Orange Frosting.

Orange Frosting:
Beat together butter or margarine, orange juice and powdered sugar.
Blend thoroughly.