In early 2007, the National Research Council’s Nutrient Requirement of Horses – Sixth Revised Edition (commonly known as the 2007 Horse NRC) was published. Given that it had been 18 years since the previous edition had been released, a substantial amount of new information was included which increased the length of the publication over the three-fold from the 1989 version. While a number of requirements or feeding suggestions did not change dramatically, there are some differences worth highlighting. Furthermore, there are some additions to the publication, such as an updated computer program, a section on ration formulation by hand, and a chapter on donkeys and other equids that many individuals will find useful. Sections are also included on feed additives, feeding behaviour, and feeding management of horses.