bran (n.)

"the husk of wheat, barley, etc., separated from the flour after grinding," c. 1300, from Old French bren "bran, scurf, scales, feces" (12c., Modern French bran), perhaps from Celtic and connected with Gaulish *brenno- "manure" (but OED is against this) or with burn (v.). The word also was used 16c. in English for "dandruff flakes."