Our objective was to determine the effects of various mixtures of lucerne (Medicago sativa, L.) and tall fescue (Festuca arundinaceae Schreb.) silages, fed to provide 1.1% of body weight as forage-neutral detergent fibre (NDF) in the diet, on milk production and composition, and associated digestion kinetic and ruminal parameters. NDF was provided from 1:0 lucerne: fescue, 0.67:0.33 lucerne:fesuce, 0.33:0.67 lucerne:fescue, or 0:1 lucerne:fescue. Diets were fed to five cows in an incomplete Latin square design (two periods). Dry matter intake increased as portion of concentrate and fescue in the diet increased. This resulted in higher milk production (P<0.05) for cow consuming diets with increasing fescue forage in the diet (32.3, 34.5, 38.9, and 40.5 kg d^-1, respectively). Milk protein increased with decreased lucerne in the diet. Milk urea nitrogen was higher for cows fed the lucerne forage diet due to its high protein solubility and high inclusion in the diet. Lower forage to concentrate ratios resulted in less indigestible fibre and higher non-structural carbohydrate in the tall fescue diet and accounted for higher milk production.