The production of bull beef may entail year round housing and storage feeding, i.e. feeding conserved forage all year, provides a simple system and avoids dietary changes. One conserved forage used is grass silage but ammonia treated straw may be an alternative. The aim of the work reported was to compare the performance of bulls storage fed on grass silage or ammonia treated long barley straw with and without additional protein with those on a traditional system involving a summer at grass.