The Effect of Graded Levels of Crude Glycerin in BRS Capiaçu Grass Silage: Fermentation Profile and Bromatological Composition

The objective of this study was to evaluate the effect of crude glycerin inclusion levels on BRS Capiaçu grass (Pennisetum purpureum) silage on the parameters of fermentation and chemical-bromatological composition. Experimental treatments consisted of BRS Capiaçu grass silage with five levels of inclusion of crude glycerin (0, 1, 5, 10 and 15% inclusion in the natural matter) during ensiling. In this study, a completely randomized design was used along with five treatments and six replicates. The inclusion of crude glycerin in BRS capiaçu grass silage linearly reduced pH (P<0.01) and effluent losses (P<0.01). For each percentage unit of glycerin addition, there was a reduction of 0.013 pH units and 0.0485% of the effluent losses. There was no effect of crude glycerin on the ammoniacal nitrogen content (P=0.82, an average of 6.65% of the total nitrogen). The variation in the dry matter content between the highest glycerin inclusion dose (15% of natural matter) and the control group (without glycerin) was 30.5%. The crude protein content (P=0.01), ash (P<0.01), neutral detergent fiber (NDF; P<0.01), neutral detergent fiber corrected for ash and crude protein (NDFap; P<0.01) and acid detergent fiber (ADF; P<0.01) linearly reduced with the inclusion of crude glycerin compare to the control group. In the same order, there was a reduction of 0.115%, 0.08%, 1.95%, 1.84% and 1.06%, respectively, for each percentage unit of glycerin added. The addition of crude glycerin in elephant grass silage vs. BRS Capiaçu up to 15% of the natural material had improved the fermentation profile and the chemical-bromatological composition.