Screening Tree Leaves for Bio-active Compounds and their Effect on In vitro Fermentation and Methane Production from Total Mixed Ration

This study was undertaken to screen the tree leaves (TLs) for bio-active compounds and assess their impact on the substrate degradation and methane production from total mixed ration (TMR) by in-vitro gas production technique. The sundried, finely ground leaves of Mangifera indica (MI; Mango), Cassia fistula (CF; Amaltas/Amulthus) and Acacia nilotica (AN; Babul) were supplemented individually and in combinations i.e. MI+CF, MI+AN, CF+AN and MI+CF+AN to TMR at 1% level on DM basis. Results revealed that the total phenols, condensed tannins, hydrolysable tannins, DPPH and vitamin C content were the highest (P<0.01) in Mangifera leaves. The saponins content was the highest (P<0.01) in Acacia leaves. Irrespective of incubation period, the net gas production (NGP) and ME were the highest (P<0.01) in TMR supplemented with combination of MI+AN. The digestibility of NDF and true OM was highest (P<0.01) in TMR supplemented with Cassia leaves, which was comparable with that supplemented with Mangifera, MI+AN and unsupplemented TMR. The highest (P<0.01) concentration of total and individual VFAs in TLs supplemented groups was observed in TMR supplemented with Mangifera leaves, followed by that supplemented with Casia leaves. The in vitro methane production was reduced significantly (P<0.01) in all the TLs supplemented groups except that supplemented with Mangifera leaves which was higher than unsupplemented TMR. The best fermentation efficiency was observed in TMR supplemented with MI+CF+AN followed by that supplemented with Casia and Mangifera leaves. The microbial biomass synthesized in TMR supplemented with Mangifera leaves was higher (P<0.01) than that of Casia supplemented and unsupplemented TMR. Irrespective of TLs supplementation, all the above parameters were higher (P<0.01) at 24h incubation as compared to that at t-half, except that the efficiency of conversion of fermented hexose to methane was higher (p<0.01) at t-half as compared to 24h incubation. It was concluded that Mangifera leaves is a rich source of bioactive compounds. Supplementation of Mangifera and Casia leaves resulted in the highest digestibility of nutrients, VFAs production, efficiency of rumen fermentation and microbial biomass synthesis; and decrement in efficiency of conversion of fermented hexose to methane from TMR.