The aims of the present study were to investigate the effects of dietary supplementation with rumen-protected taurine (RPT) on the whole-body protein turnover, the plasma metabolomics, and the whole blood cell transcriptomics in steers. Eight steers, averaging 220 ± 3.26 kg of liveweight, were allocated in a replicate 4 × 4 Latin square design. The experimental treatments consisted of four levels of RPT supplementation: 0, 25, 50, and 75 g RPT per day, added to a basal diet. The results showed that supplementation with RPT linearly decreased the fecal nitrogen (N) excretion (