How much food does a cow need per hour and water does a cow need?

The amount of feedstuffs and water that a cow needs is measured on a per-day basis, not per hour. Even then it is really dependent on the individual animal itself, especially when it comes to water requirements. As far as feed is concerned, the maintenance requirement for a cow is around 2.5% if its body weight in dry matter ration per day. As-fed ration is variable depending on many things including moisture of the feed, physiological requirements of the cow, and the time of the year.