This study aimed to evaluate the production and milk composition of crossbreed F1 Holstein × Zebu (1/2 H×Z) cows grazing on Marandu grass (Urochloa brizantha cv. Marandu) or Tifton-85 (Cynodon spp.) sup-plemented with different protein concentrate. 36 H × Z cows (±514 kg of body weight) were used. The cows had ± 65 days in milk and were distributed in a randomized block design, in a 2 × 3 factorial arrange-ment, i.e., two types of grass (Marandu and Tifton-85 grass), three types of protein supplementation (2.0 kg of concentrate with low rumen degradable protein; 2.0 kg of concentrate with high rumen degradable pro-tein; and no concentrate feed). Both grass produced similar amounts of forage mass, kg.h-1. The nutritional value for both grasses was also similar in all the variables analyzed, such as crude fat, crude protein, carbo-hydrates, non-fiber carbohydrates, neutral detergent fiber, and, acid detergent fiber. The milk yield was not affected by the different grasses used for grazing. Only the lactose content was higher in cows grazing on marandu grass than in Tifton-85 grass (P=0.032). The cows that did not receive concentrate had lower daily milk yield (P=0.010) and a lower percentage of lactose (P=0.011). In conclusion, both grasses can be used for grazing F1 ½ H × Z cows, and protein supplementation, regardless of its ruminal degradability, in this situation is necessary to increase milk production. Manuscript profile