Características fermentativas e valor nutricional de silagens de milho com óleos essenciais

Abstract

This study aimed to evaluate the effects of adding an essential oil blend (75% carvacrol and 25% cinnamaldehyde) on fermentative losses, chemical composition, and aerobic stability of corn silage (Zea mays L., cv. BRS 2223). The experiment was conducted in a completely randomized design with five replicates, using doses of 0, 200, 400, 600, and 800 mg kg⁻¹ of fresh matter applied before ensiling in laboratory silos sealed for 60 days. Analyses included chemical composition (dry matter, organic matter, crude protein, ether extract, fiber fractions, carbohydrates, in vitro digestibility), losses (gases, effluents, organic matter), fermentative profile (lactic acid, acetic acid, butyric acid, ethyl acetate, ethanol, propionic acid), and aerobic stability (temperature and pH for 177 hours). The results demonstrated significant quadratic effects for dry matter (maximum 34.5% at 200 mg kg⁻¹), organic matter (94.5% at 200 mg kg⁻¹), total carbohydrates (77.5% at 400 mg kg⁻¹), and A+B1 fraction (55% at 400 mg kg⁻¹), with a linear decrease in crude protein (reaching a minimum of 7.08% at 800 mg kg⁻¹) and a linear increase in ether extract (reaching a maximum of 3.73% at 800 mg kg⁻¹), suggesting an inverse relationship between these components, possibly due to the antimicrobial action of the blend on protein degradation and lipid retention. Gas and effluent losses were minimal at 400 mg kg⁻¹ (42% reduction compared to the control), with no differences in dry matter recovery. The fermentative profile exhibited quadratic effects for ethanol (maximum of 0.23 mg kg⁻¹ at 600 mg kg⁻¹), ethyl acetate (maximum at 600 mg kg⁻¹), and propionic acid (minimum at 400 mg kg⁻¹), with lactic acid reaching a nominal maximum of 6.86% at 200 mg kg⁻¹ without statistical significance. The levels of acetic acid, butyric acid, acetone, and methanol were unaffected, indicating selective modulation of anaerobic fermentation. Regarding aerobic stability, all doses inhibited heating, maintaining temperatures 2°C below ambient temperature, unlike the control. It is concluded that the blend positively modulates fermentation, reduces losses, and improves preservation, with doses of 200–400 mg kg⁻¹ optimizing fermentative efficiency, nutritional preservation, and aerobic stability under tropical conditions, promoting sustainability in silage production.