Inclusão de torta de oliva em silagem de milho e capim elefante

Abstract

The objective of this study was to evaluate the effect of including crude olive cake (CO; a by-product from olives processing for production of olive oil) on fermentation, chemical composition, and aerobic stability of corn and elephant grass silages. For that, an experiment was conducted with the following treatments: corn forage with 5% CO (based on fresh matter); corn forage without CO (control); elephant grass with 5% CO (based on fresh matter); and elephant grass without CO (control). The silages were produced in experimental silos (PVC tubes with 2.5 L-capacity) and stored for 99 days. After the silos were opened, the aerobic stability of silages was assessed for 10 days. The experiment was conducted in a completely randomized design under a factorial scheme 2 (two crops) × 2 (with or without CO), with three replications. There was no difference (P > 0.05) in fermentative losses for corn silage (overall mean of 63.8 g/kg of dry matter (DM)) and grass silage (overall mean of 90.8 g/kg DM) due to the inclusion of CO. Regarding the fermentative profile, butyric acid increased by 35.6% in the grass silage when treated with CO (P = 0.002) and lactic acid decreased by 30% in corn silage and almost 50% in grass silage when treated with CO (P = 0.015). Acetic acid decreased by 14.8% in corn silage and increased by 19.3% in grass silage due to application of CO (P = 0.007). Regarding the chemical composition, we observed that the content of ether extract increased on average by 53% for both crops due to the application of CO (P = 0.001). After the silos were opened, the aerobic stability of silages was not altered by the inclusion of CO (P ≥ 0.18). The inclusion of CO in the corn silage at 5% (based on fresh matter) does not alter DM losses and aerobic stability, indicating that the ensiling of corn crop with CO can be a good fate to avoid an undesirable discarding of this by-product in the environment. Moreover, the inclusion of CO in the grass silage increased numerically (107%) the effluent production and likely caused clostridial fermentations.