This study aimed to evaluate the effects of Streptococcus bovis on the fermentation characteristics and nutritive value of Tanzania grass silage. Tanzania grass was chopped and left untreated (U) or treated with Streptococcus bovis JB1 at 1 × 10(6) colony-forming units per gram (cfu/g) of fresh forage or Streptococcus bovis HC5 at 1 × 10(6) cfu/g of fresh forage and packed into sixtuplicate laboratory silos. The largest number of enterobacteria, molds and yeast (M&Y) occurred in untreated silages and the smallest populations of enterobacteria and M&Y and the largest numbers of lactic acid bacteria (LAB), at 9.81 and 9.87 log cfu/g, were observed in Streptococcus bovis JB1 and HC5, respectively (P < 0.05). Silages treated with JB1 and HC5 had lower (P < 0.05) silage pHs and concentrations of ammoniacal nitrogen (NH3-N) than untreated silages. The application of Streptococcus bovis JB1 and HC5 resulted in fewer losses through gases and effluents (P < 0.05), which resulted in greater dry matter recovery (DMR) and crude protein recovery (CPR) (P < 0.05). Streptococcus bovis JB1 and HC5 improved the fermentative profile and increased the concentration of crude protein and DMR and CPR in Tanzania grass silage.