Re: What is the chemical composition of feathers?

Feathers are largely made up of keratin, which is a protein in turn made of amino acids - in fact, feathers consist of 85% protein on a dry weight basis (that is, excluding water - another major constituent of feathers). There are some other constituents, such as oils.

A significant portion of the feather are pigments that give feathers their colors: the melanins, which darken the color; carotenoids, which give bright colors like reds, oranges, and yellows; and, porphyrins, which give red and brownish colors.

Here are some websites with more information about the chemical composition of feathers:

Chemical characterization of a feather

Recycling feathers into polyurethane