Lemongrass essential oil in sugarcane silage: Fermentative profile, losses, chemical composition, and aerobic stability

Abstract

Essential oils have been used to manipulate microbial growth in different processes such as silage fermentation. This study aimed to evaluate the effects of increasing levels of lemongrass oil (LO) in sugarcane ensiling on fermentative profile and losses, chemical composition, in vitro degradation, and aerobic stability. Thirty-two experimental silos were used in a blocked randomized design to evaluate the following treatments: control (CON), sugarcane ensiling without LO; and increasing levels of LO on sugarcane ensiling: 1 (L1), 2 (L2), and 3 (L3) mL of LO per kg of sugarcane (as-fed basis). Results of LO level effects were regressed to access the maximum/minimum points. Lemongrass oil linearly increased NH3-N and decreased the count of mold and yeast, lactic, and butyric acid concentrations. Besides, LO quadratically affected silage pH, Brix, and levels of ethanol and acetic acid. The lowest silage pH, ethanol, and acetic acid concentration were found with 1.17, 2.22, and 1.89 mL/kg of LO. Lemongrass oil quadratically affected fermentative losses, dry matter (DM) recovery, and chemical composition of silage. The lowest total losses were found at 1.53 mL/kg of LO, whereas the highest DM recovery was obtained using 1.90 mL/kg LO. Intermediary levels of LO (1.99–2.00 mL/kg) improved silage DM, organic matter, non-fiber carbohydrate, and ether extract content, whereas reduced silage concentration of neutral detergent fiber, acid detergent fiber, lignin, and crude protein. Lemongrass oil did not affect neutral detergent fiber in vitro degradation and quadratically affected DM degradation of silage, whereas linearly increased silage aerobic stability (h) and temperature of silage between 48 and 104 h after aerobic exposure. Thus, intermediary levels (between 1.53 and 2.22 mL/kg) of LO reduces ethanol concentration and fermentative losses of silages, improving DM recovery, chemical composition and DM degradation of sugarcane silage. Additionally, LO levels linearly decrease yeast and mold count and increase the aerobic stability of sugarcane silage.