Definition of "offal"

The whole of the corn offal is better food than wheat straw, but its blades and tops are so greatly superiour, that cattle prefer them to hay, and will fatten on them as well.

1817, John Taylor, Arator; Being a Series of Agricultural Essays Practical and Political in Sixty-One Numbers, Baltimore: John M. Carter, No. 32, Indian Corn, p. 96

Our standard wheat flour contains only the endosperm and represents practically a 75 per cent. extraction. The remaining 25 per cent. is known in the trade as grain offal or mill-feed, and is used largely as a concentrated food for live stock, being prized in the feeding of dairy cattle.

1918, Alonzo Englebert Taylor, War Bread‎, New York: Macmillan, page 75

[…] the fragments are broken down and the finer particles are collected by sieving; finally, there is the bolting of the assembled fine fractions, with exclusion of the wheat offal which includes bran and a number of other commercial fractions like red dog and shorts.

1941, Wheat Studies of the Food Research Institute‎, volume 18, Stanford University, page 96