Ensiling is a helpful process to ensure food availability and support animal production. However, a good fermentation is required to avoid nutritional and economic losses. Lactic acid bacteria (LAB) are used to favor homolactic fermentation and inhibit the growth of undesirable microorganisms. The objective of this study was to evaluate the changes on the fermentation profile, chemical composition and microbial populations of alfalfa silages harvested in January (cut 1, C1) and March (cut 2, C2), treated with LAB strains. The alfalfa was harvested at the early flowering stage, using a backpack mower, in 2016. The LAB strains used were isolated from alfalfa silage in a prior study and the commercial inoculant (CI) was the Sil All (Alltech, Brazil) which contains Lactobacillus plantarum, Pediococcus acidilactici, Enterococcus faecium, and L. salivarus ssp. salivarus. The inoculants (I) evaluated were: 1. No inoculant (Control); 2. L. plantarum (AV 14.17); 3. Mixture of L. plantarum, L. brevis and P. acidilactici (Combo); and 4. CI. The experiment was analyzed as a completely randomized design in a 4 × 2 factorial arrangement, with 4 replicates. All inoculants were applied at the rate of 10⁶ cfu/g fresh matter. The silages were stored for 90 d. The means were separated by Tukey’s test (P ≤ 0.05). There were I × C interactions for WSC, lactic to acetic acid ratio (L:A), NDF and ADF. Silage from C2 treated with AV 14.17 had higher WSC, while both silages treated with AV 14.17 and Combo had higher L:A. Additionally, lower NDF and ADF contents were found in silages inoculated with CI and Combo, respectively. The silage treated with the AV 14.17 had the lowest pH, with average of 4.41. NH₃-N was lower in silages treated with Combo and CI, as well as, in silages of C2 compared with C1. The DM was higher for silages treated with inoculants (376.6 vs. 370.9 g/kg). It was observed the highest CP value for C2 silages (150.3 g/kg of DM). The C2 silages had higher lactic and lower acetic acids. The LAB and yeast counts were higher and mold count was lower in C1 silages. The wild LAB strains improved the fermentation profile on alfalfa silage in tropical conditions. Supported by CNPq, CAPES, and INCT-CA