Cattle Market Transparency Act of 2021 This bill directs the Department of Agriculture (USDA) to establish and maintain a library or catalog of each type of contract offered by packers to producers for the purchase of all or part of the production of fed cattle (including cattle that are purchased or committed for delivery). Fed cattle means a steer or heifer that has been feeding on a ration of roughage and feed concentrates prior to slaughter, including grains, protein meal, grass, and other nutrient-rich feeds. USDA must create and maintain a publicly available library of the types of contracts that are being offered by packers to, and are open to acceptance by, producers for the purchase of fed cattle. Additionally, USDA must also establish (1) regional mandatory minimum thresholds to enhance price discovery and transparency for cattle market participants; and (2) methods for establishing such thresholds, which shall be publicly available. Further, the bill revises daily reporting requirements for packer processing plants by requiring them to include the number of cattle scheduled to be delivered for slaughter each day for the subsequent 14 days.