This research aimed to measure the microbiological, chemical composition profile and fermentative characteristics during storage of fresh olive bagasse, in natura and incorporated with corn, soybean and rice brans, respectively. The experimental design was completely randomized, with the plots constituting the four main treatments (olive bagasse in natura or with added corn, soybean and rice brans, respectively), and the subplots allocated the three sampling times, which corresponded to time

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... o (at the ensilage moment) and 28 and 56 days of ensilage. The fermentative characteristics (dry matter content [DM], pH and ammoniacal nitrogen [NH3-N], microbiological profile (populations of filamentous fungi, lactic acid bacteria, enterobacteria and Clostridia) and chemical composition profile (mineral matter, organic matter, crude protein [CP], ether extract, neutral detergent fiber, acid detergent fiber, lignin, cellulose and hemicellulose) were determined. The corn grain and rice meal treatments, which demonstrated pH 4.08 and 3.96 at 28 days of fermentation, respectively, provided the best fermentation profile. After storage for 56 days, the samples with added soybean and rice meal reached the highest levels of CP (166.15 and 93.78 g kg-1 DM), respectively. Increasing the storage period reduced the pH of the obtained silages but increased the losses of DM, NH3-N and contributed to the losses of some nutrients. Rice meal and corn grain have been recommended to be used as additives in olive bagasse storage. However, the choice of additives studied is dependent on their commercial availability in each region.