Determination of in vitro Gas Production Kinetics by Adding Leucaena leucecophala and Corn Oil to the Ration in Different Ratios

This study was aimed to determine in vitro gas production kinetics and organic matter digestibility (IVOMD) of ration added by Leucaena leucecophala and corn oil (CO) at various ratios. Four levels of Leucaena leucecophala (0%, 25%, 50%, and 75%, DM basis) and three levels of corn oil (0%, 1%, and 2% of substrate) were arranged in a 4 × 3 factorial design. Hohenheim in vitro gas production procedure was employed to determine gas production kinetics, IVOMD, and partitioning factor (PF) value of the experi-ment. Supplementation of leucaena at 25% (L25) increased IVOMD (%), potential degradation fraction, cumulative gas production (GP) (mL), and metabolizable energy (ME) value (MJ/kg DM) of the ration (P<0.01). There was no effect on in vitro gas production kinetics when leucaena was given at higher levels in comparison with L25 (P>0.05). Besides, corn oil supplementation to the substrate did not negatively affect IVOMD and gas production kinetics. Instead, 2% of corn oil supplementation increased GP (P<0.05). Indicator for microbial efficiency as measured with PF value increased with leucaena and CO supplementa-tion (P<0.05). The results indicated that incorporation of 25% leucaena and 2% of corn oil in the ration improved in vitro organic matter digestibility and gas production kinetics while a higher rate of supplemen-tation did not give significant contribution in term of gas production on in vitro rumen fermentation system. Further study in chemical and biological treatment of leucaena or tannins sources and corn oil is needed to investigate specific mechanisms in modulating rumen fermentation in vitro and in vivo.