Methane mitigation potential of phyto-sources from Northeast India and their effect on rumen fermentation characteristics and protozoa in vitro

AIM: The aim of the study was to explore the anti-methanogenic potential of phyto-sources from Northeast region of the country and assess the effect on rumen fermentation characteristics and protozoa for their likely inclusion in animal diet to reduce methane emission. MATERIALS AND METHODS: Twenty phyto-sources were collected from Northeast state, Assam, during March to April 2014. Phyto-sources were analyzed for their tannin content followed by screening for methane mitigation potential using in vitro system. The effect of tannin on methane production and other fermentation parameters was confirmed by attenuating the effect of tannin with polyethylene glycol (PEG)-6000 addition. About 200 mg dried phyto-source samples were incubated for 24 h in vitro, and volume of gas produced was recorded. The gas sample was analyzed on gas chromatograph for the proportion of methane in the sample. The effect of phyto-sources on rumen fermentation characteristics and protozoal population was determined using standard methodologies. RESULTS: Results from studies demonstrated that Litchi chinensis, Melastoma malabathricum, Lagerstroemia speciosa, Terminalia chebula, and Syzygium cumini produced comparatively less methane, while Christella parasitica, Leucas linifolia, Citrus grandis, and Aquilaria malaccensis produced relatively more methane during in vitro incubation. An increase (p<0.05) in gas and methane production from the phyto-sources was observed when incubated with PEG-6000. Entodinimorphs were prominent ciliates irrespective of the phyto-sources, while holotrichs represented only small fraction of protozoa. An increase (p<0.05) in total protozoa, entodinimorphs, and holotrichs was noted when PEG-6000 added to the basal substrate. Our study confirmed variable impact of phyto-sources on total volatile fatty acid production and ammonia-N. CONCLUSION: It may be concluded that L. chinensis, M. malabathricum, L. speciosa, S. cumini, and T. chebula are having potent methane suppressing properties as observed in vitro in 24 h. These leaves could be supplemented in the animal diet for reducing methane emission; however, in vivo trials are warranted to confirm the methane inhibitory action and optimize the level of supplementation.