Potential of eucalyptus (<i>Eucalyptus camaldulensis</i>) essential oil to modify in vitro rumen fermentation in sheep

This study aimed to evaluate the effects of increasing doses (0, 10, 20, 40, 80 and 120 µl/50 ml) of essential oil of Eucalyptus (Eucalyptus camaldulensis) on in vitro rumen fermentation. Two 24 h-incubations were done and gas production (GP) was measured. The liquid was collected for analysis of ammonia nitrogen (NH3-N) and true organic matter degradability (TOMD). The partitioning factor (PF) was estimated after 24 h of incubation. Procedure of H-NMR spectroscopy was used to analyse rumen fluid samples. Results showed that, GP was only affected and decreased significantly for the doses 20, 40, 80 and 120 µl. Ammonia-N concentration was reduced by 8.2%, 18.6%, 21.6% and 25% when 20, 40, 80 and 120 µl of EuEO were added respectively. The TOMD values were decreased significantly at doses 40, 80 and 120 µl. The PF values were affected between doses control and 120 µl. Concerning H-NMR spectroscopy, results showed that the diet containing 80 µl of EuEO, there were increases observed in the concentration of rumen methylamine, glucose, butyrate, propionate and glycine. EuEO modified fermentation trends in the rumen, mainly by reducing GP and protein deamination. And the use of EuEO in high concentrations inhibits ruminal flora and decreases the production of VFA.