When autumn calving dairy cows are offered low levels of compound supplement, milk production and subsequent profitability depends not only on silage quality but also the quantity of silage consumed. Silage quality and palatability are undoubtably related but when grass silage contributes in excess of 75% of total dry matter intake, some silages which, to date, would be defined as being of good quality, appear comparatively less palatable than their chemical analyses would initially suggest, To enable accurate ration formulation in dairy feeding systems based on ad libitum grass silage, a prediction of silage dry matter intake is essential. In this experiment nine silages, all with a high digestibility and crude protein content, but varying in their fermentation characteristics, were offered ad libitum to individually fed October calving dairy cows receiving 3 kg of a 160 g/kg crude protein cereal based compound supplement daily.