LAUSR

The present study was conducted to examine the plant bioactive compounds individually and in association for modulation of rumen fermentation in buffalo ( Bubalus bubalis ) with the aim to develop phytogenic feed additive for enteric methane mitigation from ruminants. The extracts of Sapindus mukorossi (SMF) fruits (aqueous and ethanolic) as a source of saponins, Ficus bengalensis (FBL) leaves (aqueous and acetonic) as a source of tannins and Eucalyptus globulus oils (ECO) as a source of essential oils were prepared and evaluated individually and in association for their effect on feed fermentation and methanogenesis by four separate in vitro experiments. Each experiment was conducted as a completely randomized design using a control and various treatment groups with different concentrations of plant bioactive compounds and their blends. Rumen fluid inoculum was collected from four rumen fistulated Murrah ( B. bubalis ) buffalo steers. The in vitro incubations were carried out for a period of 24 h with five replicates for each treatment. For SMF and FBL extracts, a concentration of 0, 0.5, 1.0, 2.0 and 4.0 mL were tested, whereas, ECO was tested at the levels of 0, 20, 40, 80 and 120 µL per 40 mL buffered rumen fluid with 0.4 g of oats hay as substrate. Both aqueous or ethanol extracts of SMF, acetonic extract of FBL, and ECO showed linear decrease ( p  < 0.001) in methane production with increasing concentrations of plant compound. Out of four blends tested, blend-1 (ECO, 125 µL; SMF aqueous extract and FBL acetonic extract, 6.25 mL each per L rumen fluid) showed reduced methane production without affecting negatively to rumen fermentation at much lower individual doses, representing positive associative effect. It is implied that the extracts from S. mukorossi fruits, F. bengalensis leaves and E. globulus essential oils and their blends have the potential to act as anti methanogenic agents. A positive associative effect in reducing enteric methanogenesis in their blends signifies their application as the phytogenic feed additive in ruminants.