21 C.F.R. § 573.540 – Hydrolyzed leather meal.

(a) Identity. Hydrolyzed leather meal is produced from leather scraps that are treated with steam for not less than 33 minutes at a pressure of not less than 125 pounds per square inch.
(b) Specifications. The additive shall conform to the following percent-by-weight specifications:
Moisture, not less than 5 percent nor more than 10 percent. Crude protein, not less than 60 percent. Crude fat, not less than 5 percent. Crude fiber, not more than 6 percent. Chromium, not more than 2.75 percent.
(c) Use. It is used or intended for use as a source of protein in swine feeds in an amount not to exceed 1.0 percent by weight of the finished feed.
(d) Labeling. The labels and labeling shall bear, in addition to the other information required by the Act:
1. (1) The name of the additive, hydrolyzed leather meal.
2. (2) Adequate directions to provide finished feeds complying with paragraph (c) of this section.