In grass-based dairy systems, concentrate (Cc) may be allocated at various times of the lactation to support milk production and reproductive performance. To assess the benefits of Cc supplementation, an experiment combining 3 dairy breeds (Holstein, Normande and Jersey) and 4 Cc strategies was carried out at the INRAE Le Pin experimental farm. In comparison with a zero Cc group (C0), the same daily quantity of concentrate (3 kg for Je and 4 kg for Ho and No) was distributed during 100 days, at three periods of the lactation (early-C1, middle-C2 and late-C3). Each year, the 144 to 168 cows are managed under a 3-month compact spring-calving system, and grazed in a single herd with a simplified rotational grazing system (180 to 220 days). On average, the milk yield (MY) and composition response and the body condition score (BCS) show changes differ according to the breed and period of Cc allocation. The MY response of the Je cows (0.70 kg (kg Cc)–1) is lower than the Ho and No cows (0.85kg (kg Cc)–1), but higher if the MYis expressed taking account the fat and protein content. Early in lactation, the Cc has no favourable effect on the BCS change, but Cc improves the BCS at the end of the 100 days, in the middle and at the end of lactation. The period of Cc allocation determines the partitioning of nutrients between MY and BCS change.