The Cornell Net Carbohydrate and Protein System (CNCPS) model was used to evaluate pasture, maize, lotus, and sulla silage supplements for grazing dairy cows. Base data were obtained from a New Zealand study comparing six dietary treatments. Each treatment consisted of 10 cows and included one ad libitum pasture allowance treatment and a restricted pasture allowance treatment. These data plus digestion kinetic information were used as inputs to the CNCPS model to determine the first-limiting nutrient and to provide information concerning rumen digestion parameters. The value of these silages as either supplementary or complementary feeds for grazing dairy cows was identified.