Home › CFR › Title 21 › Part 58921 CFR Part 589 — Substances Prohibited from Use in Animal Food or FeedSubpart A — General Provisions§ 589.1— Substances prohibited from use in animal food or feed.Subpart B — Listing of Specific Substances Prohibited From Use in Animal Food or Feed§ 589.1000— Gentian violet.§ 589.1001— Propylene glycol in or on cat food.§ 589.2000— Animal proteins prohibited in ruminant feed.§ 589.2001— Cattle materials prohibited in animal food or feed to prevent the transmission of bovine spongiform encephalopathy.