Exogenous Fibrolytic Enzymes and Length of Storage Affect the Nutritive Value and Fermentation Profile of Maize Silage

The addition of exogenous fibrolytic enzymes (EFEs) and length of storage can affect the quality of maize silage. Therefore, the objective of this study was to evaluate the fermentative profile and the nutritive value of maize silage treated with different doses of EFEs ensiled for 30, 60, or 90 days. The study was designed as completely randomized in a split-plot arrangement of treatments, where four doses of EFEs were assigned to the main plot and three lengths of storage to the sub-plot, with four replicates per treatment. Treatments were: Control, E100 (EFEs at 100 g/ton dry matter (DM)), E150 (EFEs at 150 g/ton DM) and E200 (EFEs at 200 g/ton DM). The EFE treatment did not increase the digestibility of nutrients but increased the acetic acid concentration (1.87 vs. 1.18% DM), while decreasing the content of ethanol (0.02 vs. 0.08% DM), ethyl lactate (7.50 vs. 15.9 mg/DM) and ethyl acetate (5.58 vs. 10.6 mg/DM). Prolonged storage increased DM losses (7.05 vs. 2.32%) and acetic acid content (2.19 vs. 1.03% DM), but decreased ethanol concentration (0.02 vs. 0.09% DM). In conclusion, the addition of EFEs in maize silages did not affect nutrient digestibility and DM losses during fermentation, but it slightly decreased the concentrations of ethanol and esters and increased the acetic acid content. Although statistically significant, such differences may not be relevant biologically, due to the relatively low concentrations of ethanol and esters in all treatments.