The objective of this study was to evaluate the effects of regrowth age (RA) and cutting time (CT) of elephant grass (Cenchrus purpureus cv. Cameroon) on the fermentation profile, microorganism population, and nutritive value of the silage in two simultaneous trials at different sites. A 2 × 2 factorial scheme with two CTs (08:00 and 14:00) and two RAs (8 and 16 weeks) at ensilage was used in a completely randomized design, with four replicates in each trial, totaling 16 experimental units per trial. Results showed that ammonia nitrogen to total nitrogen content (N-NH3/TN) ranged from 71.8 (14:00; 16 weeks) to 137.0 g kg -1 (14:00; 8 weeks). Elephant grass silage harvested at 14:00 at 8 weeks had the lowest pH (3.53) and highest lactic acid content (39.7 g kg-1 dry matter). The in vitro dry matter digestibility (IVDMD) was higher (P < 0.05) in the silage of plants harvested at 8 weeks than in the silage harvested at 16 weeks (59.9 vs. 46.8%, respectively). In trial 2, elephant grass silage harvested at 14:00 had lower pH and acetic acid content. The IVDMD was higher in elephant grass silage harvested at 14:00, with values of 65.3% and 56.2% at 8 and 16 weeks, respectively. We recommend elephant grass harvested at 8 weeks of regrowth and cut at 14:00 to produce silage with better nutritive value and fermentative profile.

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The study objective was to evaluate the effects of the addition of exogenous protease on the fermentation and nutritive value of rehydrated corn and sorghum grain silages during various storage periods. Treatments were applied using a 2 × 6 × 3 factorial combination, with 2 types of rehydrated grains (corn and sorghum), 6 doses of the enzyme (0, 0.3, 0.6, 0.9, 1.2, and 1.5%, based on natural matter) and 3 fermentation periods (0, 60, and 90 days) in a completely randomized design, with 4 replications. The protease aspergilopepsin I, of fungal origin, produced by Aspergillus niger, was used. The lactic acid concentration increased linearly as the enzyme dose increased in corn (CG) and sorghum (SG) grain silages, at 60 and 90 days of fermentation. There was an increase in the concentrations of ammonia nitrogen and soluble protein, as well as the in situ starch digestibility in rehydrated CG and SG silages, compared to the treatment without the addition of protease. The addition of 0.3% exogenous protease at the moment of CG ensiling and 0.5% in rehydrated SG increased the proteolytic activity during fermentation, providing an increase in in situ starch digestibility in a shorter storage time.