The effect of blend essential oil and NaNO₃ addition on in vitro gas production kinetics and nutrient digestibility

The objective of this study was to determine the effect of the addition of blend essential oil (BEO) and NaNO₃ on in vitro gas production kinetics and nutrient digestibility. Blend essential oils consisting of essential oil pine (Pinus merkusii) and Eucalyptus (Melaleuca leucadendra) in the ratio of 1:3. The feed for the fermentation substrate consisting of Pennisetum purpureum cv. Mott, rice bran, and pollard in the ratio of 60:20:20 based on dry matter. The doses of BEO added to the feed substrate in rumen fermentation are 0 µl/L and 200 µl/L of fermentation medium combined with 0 % and 0.1% level of NaNO₃. This study used in vitro gas production technique according to Menke and Steingass (1979). Fermentation was conducted at 39°C for 24 hours. Fermented gas production was measured at 1,2, 4, 6, 8, 12, 24 hours. Gas produced during fermentation was used to determine gas production kinetics. Collected data included gas production and nutrient digestibility of dry matter (DMD), organic matter (OMD), crude protein (CPD), and crude fiber (CFD). The effect of adding blend essential oil, NaNO₃ and a combination of both were analyzed using a completely randomized design with a 2 x 2 factorial pattern. If there was a significant difference, the Duncan’s New Multiple Range Test (DMRT) was continued. Statistical analysis calculations were carried out with the help of Statistical Product and Service Solution (SPSS) personal computer software. The addition of BEO caused a decrease in CPD and fraction a (P<0.01). The addition of NaNO₃ caused a decrease in CPD, fraction a, fraction a+b (P<0.01) and decreased fraction b, fraction c (P<0.05). The addition of BEO and NaNO₃ had no effect on DMD, OMD, and CFD (P>0.05). The interaction between BEO and NaNO₃ did not show a significant effect on all digestibility parameters and gas production kinetics. The conclusion of this study is that the addition of BEO and NaNO₃ does not interfere with gas production kinetic and nutrient digestibility in the rumen in vitro.