In vitro screening of rumen fluid samples from indigenous African ruminants provides evidence for rumen fluid with superior capacities to digest tannin-rich fodders

The capabilities of rumen fluid sources from indigenous African ruminants a nd hindgut fluid from zebra to ferment leaves of Acacia angustissima, Calli andra calothyrsus, Leucaena diversifolia, Leucaena leucocephala, Leucaena p allida, and Tephrosia bracteolata were evaluated to determine the presence of tannin tolerant or degrading microbes. In vitro gas and ammonia producti on and loss of neutral detergent fibre were estimated as indices for fermen tation. The effect of polyethylene glycol (PEG) on fermentation was tested. The ability of microorganisms in rumen fluid sources to grow in the presen ce of tannin extracts or tannic acid was also tested and their disappearanc e was determined by HPLC. There was a significant (P < 0.001) rumen fluid s ource x fodder type interaction with all variables studied. The highest gas and ammonia production was from samples incubated with rumen fluid from di k-dik and goat. Addition of PEG enhanced fermentation with various rumen fl uid sources and from some plant leaves but its effect was greatest (P < 0.0 01) in A. angustissima. HPLC results showed that tannin and phenolic monome rs were hydrolysed by all rumen fluid sources. The conclusion from this wor k was that rumen fluid from goat, gazelle, Gunther's dik-dik, and impala ef fectively fermented tannin-rich fodders and therefore may harbour tannin to lerant or degrading microorganisms.