Increased use of whole-plant maize for anaerobic digestion (AD) in Europe raises the question: Are maize cultivars developed for use in animal nutrition equally appropriate as feedstock for AD or should different phenotypes be selected? The main objective in growing whole-plant maize as feedstock for AD is maximum output of methane per hectare. There is less need for rapidly digested plant components such as starch in AD feedstock than in a ruminant diet because the typical digestion period is several weeks for AD compared with less than two days for the rumen. The ideal phenotype of maize for AD is a very high yielding plant with a low lodging score. Metabolisable energy (ME) intake from forage is a limiting factor to output of animal product per head, thus, in addition to high dry matter yield per hectare, a high concentration of ME in the maize plant is desirable. Major factors contributing to high ME in whole-crop maize are starch and digestible plant cell wall. The ideal phenotype of maize for animal nutrition is therefore a plant with a high proportion of ear, a low concentration of lignin, high cell wall digestibility and low lodging score.