An up-to-date review of the pasture and supplementary feed resources available to the New Zealand pastoral livestock industry, and the energy and protein requirements of these livestock. The interactions between animals and their feed resources ultimately determine both the quantity and quality of the feed consumed and thus the level of animal production. An understanding of this area is key to the successful allocation of feed resources. Although the principles discussed in the early chapters are common to all grazing animals, certain aspects of their application are species or system specific, and chapters address these issues. The environmental impact of grazing pastures and supplementing grazing animals is also addressed.