The National Organic Program (NOP) rules say that if a bedding is used and animals may consume it, it must be produced under NOP rules. Well-fed animals will not consume most bedding materials. However, if waste hay, rice hulls, or other feed by-products that animals are more likely to consume are used, they must be produced organically.
This area of the farm plan and the production system is verified by the organic certifier, and each certifier may interpret this rule a little differently. Check with your certifier about the type of bedding you are using if it is likely to be consumed by your cattle.