Methane production from the rumen fermentation of Algerian Acacia tree foliage
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Date
2014
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om.ciheam.org
Abstract
Abstract. The present study was carried out to determine the in vitro methane production from the rumen fermentation
of Acacia tree leaves (Acacia nilotica, A. cyanophylla, A. albida, A. horrida and Albizia julibrissin) and
its reduction by the addition of a tannin-blocking agent (polyethylene glycol, PEG). Gas production was determined
when foliage from the five plant species was incubated in diluted rumen fluid for 6, 12, 24 and 48 h,
and methane was measured after the incubation at 24 h. The incubations were conducted either without or
with the addition of the tannin binder polyethylene glycol (PEG-6000). This has been considered a bioassay
of tannin activity, represented by the increase in gas (methane) production upon the addition of PEG (i.e.,
when tanning are neutralized). The ratio +PEG/-PEG (in total gas production) was highest for A. nilotica (2.23
and 1.75 at 12 h and 24h), followed by A. cyanophylla (1.73 at 48 h), reflecting the high amount and biologi -
cal activity of tannins in these plants. PEG addition increased methane production for all the Acacia species,
thus confirming that tannins in these samples affected methanogenesis. An increase in total volatile fatty acid
concentration in samples with addition of PEG was observed only with A. nilotica and A. cyanophylla. Tannins
contained in these plants could be of interest to reduce methane production, providing that other parameters
of ruminal fermentation were not inhibited.