In Vitro Digestibility and Methane Production as Affected by Incorporation of Different Levels of Solid State Fermented Biomass in Total Mixed Rations

Abstract

The aim of this study was to evaluate the effect of incorporating different levels of solid state fermented (SSF) biomass on in vitro digestibility and methane (CH4) production. The total mixed rations (TMRs) were prepared using concentrates (40%), wheat straw (30%), groundnut straw (30%) and used as substrate for in
vitro studies. The SSF biomass was prepared using Aspergillus oryzae and Trichoderma reesei spp. of fungi. The enzyme carboxymethyl cellulose having activity of 680 IU/g was incorporated in TMRs @ 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by replacing wheat straw on part basis. The in vitro apparent and true dry matter digestibility (DMD) of TMR increased with increasing levels of SSF biomass in the TMR. The highest in vitro apparent and true DMD was found at inclusion of 5% SSF biomass which increased (P<0.01) by 14.36 and 12.92%, respectively. Digestibility of OM increased (P<0.01) by 13.94% as compared to control group. With increasing levels of SSF biomass, in vitro CH4 production reduced as compared to control TMR and the maximum
reduction was observed at inclusion level of 5% SSF level. In vitro CH4 production (mL/100 mg DM) reduced (P<0.01) by 16.91% than the value observed in control group. Methane production in terms of mL/100 mg apparent and true DMD reduced (P<0.01) by 27.55 and 26.80%, respectively as compared to control group.
Therefore, inclusion of SSF biomass in the TMRs at 5% level has the potential for improving digestibility and reducing CH4 production in ruminants, however, in vivo studies need to be conducted for substantiation of in vitro results.