The introduction of milk quotas has resulted in a trend towards minimising the costs of producing each unit of milk output. The first step in achieving this is through increased forage use and minimising the input of high cost supplementary feeds, an approach widely adopted at present. Further reductions in costs can be achieved if the cost per unit of supplementary feed can be reduced. One such approach is through replacing conventional dairy concentrates, either conventional purchased dairy rations or home mixed barley/soya bean rations, by single feeds which require no mixing or processing prior to feeding to the animals. Maize gluten feed offers potential in this area but although data on its energy and protein values are known there is little direct information available on its value when offered, especially as the sole supplement, to lactating cows. The present study was set up to compare the values for lactating cows of maize gluten feed, either offered as the sole or part of the supplement, with that of more conventional purchased concentrate or a barley/soya bean ration of similar crude protein content.