Nutritional value and Fermentative profile of elephant grass silage under levels of crude glycerine

Crude glycerin was used at Elephant grass (Pennisetum purpureum cv. Napier) ensiling in order to know the effects on the chemical composition and fermentation profile of silages. Elephant grass (120 d of growth) was ensiled either without (control) or with 1%, 5%, 10%, and 15% of crude glycerin (as-is fresh matter) in a completely randomized design, with tree replicates. Silos remained closed for 60 d. Data were analyzed using the REG procedure of SAS (v. 9.0). The use of crude glycerin increased by 21.3% the content dry matter (DM) (P<0.05). Between levels, there was increase 0.35% on the content DM for each percentage unit of glycerin added (?_DM = 20.8+ 0.36X; R? = 0.95). The inclusion of glycerin did not affect (P>0.05) the crude protein and acid detergent fiber, average of 5.5% and 67.5%, respectively. However, it increased 56.8% the ether extract (EE) (P>0.05) compared to control silage (2.42% DM). For each 1% of added glycerin there was been increased 0.31% in EE content (?_EE = 1.7+ 0.32X; R? = 0.96). Despite the fermentation profile, the addition of glycerin decreased 44.5% in the effluent losses compared to control silage (51.31%) (P<0.05). Between levels, the decrease was 1.14% for each percentage unit of glycerin added (Y_EL= 50.02 - 1.14X; R²= 0.96). Similar behavior was observed in the variable gas loss, which was verified a reduction of 40.3% in the control silage (6.6%) and 15% inclusion of crude glycerin (P<0.05). The inclusion of crude glycerin in Elephant grass silage did not affect (P>0.05) pH values, average of 3.91. Ammonia-N concentration showed a quadratic behavior and the lowest values (6.05% total nitrogen) were observed at the level of 8.85% glycerin (P<0.05). The addition of up to 15% crude glycerin in natural matter of Elephant grass during ensilage improves the nutritional value and reduces losses during the fermentation process.