Body condition score (BCS) is a good estimate of body reserves and could serve as a proxy to prevent some metabolic disorders. Based on 686 lactations from three experimental farms, we investigated to what extent BCS direct genomic values (DGV) from the national evaluation, estimated independently from the phenotypes of this study, reflect profiles of body reserves along lactation, and how it affects body weight, feed intake and milk production. A model including different regressions of BCS DGVs was applied to each trait over the lactation period. Differences in BCS DGV resulted in differences in observed BCS and body weight during the entire lactation. Differences in daily milk production reached 1kg per day all along lactation. Interestingly, feed intake increased more rapidly with BCS DGV in early lactation but was similar thereafter. The BCS index is a promising tool to limit intense mobilization in early lactation but still needs further investigation.