N.H. Rev. Stat. Ann. § 435:13

All horses shall receive roughage in proportion to their size, age, temperament and amount of work they are required to perform. Grain may also be required when roughage alone will not meet their daily nutritional requirements. All horses shall be fed on a regular daily schedule, and all food shall be clean and free from excessive moisture. All horses shall have available a sufficient quantity of fresh water to maintain hydration.