The Daya Bay Reactor Neutrino Experiment consists of eight functionally identical detectors placed underground at different baselines from six 2.9 $\mathrm{GW}_{th}$ reactor cores. Since Dec. 2011, the experiment has collected more than 2.2 million inverse beta decay (IBD) candidates, enabling a precision measurement of the absolute reactor antineutrino flux and spectrum, and their fuel-dependent evolution. The comparison between measured spectrum and predictions from Huber-Mueller model revealed a 2.9 $\sigma$ deviation for the whole energy region and mostly pronounced in the region around 4-6 MeV. The measurement of the evolution of the reactor antineutrino flux and spectrum showed a 2.8 $\sigma$ discrepancy in the antineutrino flux variation with respect to the reactor fuel composition. The discrepancy suggests an overestimation of the predicted contribution from the $\mathrm{^{235}U}$ fission isotope and indicates that this isotope could be primary contributor to the reactor antineutrino anomaly.