Cal. Code Regs. tit. 3 § 662
When animals are fed in the milking barn, adequate feed storage facilities shall be provided. Feed storage rooms, when installed, shall be partitioned from the milking barn and shall be fly and rodent proof. The feed discharge area of bulk feed storage shall be paved with concrete or equivalent, curbed, and drained. Bulk feed may discharge directly into the barn. When a bulk feed tank is located opposite the passageway, it shall be no closer than 6 feet from the milk house. Overhead feed storage is permissible if fly, rodent, and dust tight. Feed shall be conveyed to the manger or feed box in a tightly closed dust-free system. Dust tight overhead metal feed tanks may be used. Where an overhead feed storage room is provided, it shall be tight and readily cleanable and the ceiling of the milking barn below such room shall be of smooth cement plaster or equivalent. Any part of the loft or superstructure used as an entryway shall be smoothly finished and readily cleanable.
Cal. Code Regs. Tit. 3, § 662