Resumen:
The effects of eucalyptus oils on ruminal fermentation of two agro-industry byproducts (corn stalk and oat straw), were studied using the in vitro gas production (GP) technique. Eucalyptus oil was added at 0, 30, 90, and 180 mg/l of incubation medium (equal to 0, 1.2, 3.6, and 7.2 mg/g DM substrate). Gas volumes were recorded at 2, 4, 6, 8, 10, 12, 24, 36, 48 and 72 h of incubation, and substrate DM, neutral detergent fiber (NDF) and acid detergent fiber (ADF) degradability were determined at 72 h of incubation. Eucalyptus oil increased (P<0.05) the asymptotic GP and GP of corn stalks and oat straw. Eucalyptu oil decreased fermentation pH (P<0.05) of corn stalks and oat straw. The inclusion of eucalyptu oil increased (P<0.05) DM degradability of corn stalks, oat straw. Eucalyptus oil decreased NDF degradability of corn stalks, with weak effects on NDF degradabilitie of oat straw. It can conclude that the application of eucalyptu oil positively affected rumen fermentation of the two agro-industry byproducts as roughage feeds. Increasing the dose of oils inclusion, enhanced the fermentation parameters; where the dose 180 mg oil/l increased GP, while the doses 30 and 90 mg oil/l increased nutrients digestibility.