Prediction of voluntary food intake is Important in the formulation of rations for dairy cows. There are a number of prediction models which perform relatively well for diets based on dry forages but not for silage based diets (Neal, Thomas and Cobby, 1984). Prediction of intake of silage based diets is particularly important in the UK where 0.85 of the conserved forage fed to dairy cows is silage. A large and increasing proportion of herds are fed silage ad-libitum and concentrates at a flat rate. This study was an attempt to produce better prediction models for voluntary intake of silage by dairy cows under this feeding regime.