Rations for pregnant ewes in the UK are often based on grass silage. However, due to a number of factors, the cost of producing high quality grass silage has increased significantly in recent years so lower cost alternatives need to be investigated. Production of forage maize has the potential to reduce forage costs on mixed beef/sheep farms, with high dry-matter yields (comparable to that of a 3-cut silage system) of high quality maize silage possible from a single harvesting operation (Easson and Fearnehough, 2000). However there is limited information on the effects of feeding maize silage to pregnant ewes. Alternatively, grass silage could be eliminated from rations by feeding high grain diets. The aims of this study were to evaluate the effects of replacing grass silage with either maize silage or concentrates on the performance of housed pregnant ewes and their lambs.