Micro-algae as potent rumen methane inhibitors and modifiers of rumen lipolysis and biohydrogenation of linoleic acid
Boeckaert, C.; Mestdagh, J.; Clayton, D.; Fievez, V.
Communications in Agricultural and Applied Biological Sciences 69(2): 127-130
2004
ISSN/ISBN: 1379-1176 PMID: 15560204 Document Number: 568280
This study was conducted to determine the effect of docosahexaenoic acid (DHA) microalgae on methane production as well as on lipolysis and biohydrogenation of linoleic acid (C18:2 c9c12). Rumen fluid (5 ml) from 2 fistulated wethers fed with hay/concentrate diet mixed with phosphate buffer was used as inoculum for the in vitro incubation. A DHA-rich edible algae product was tested at three levels (I, II and III). It was observed that increased amounts of free DHA also resulted in higher methane inhibition. Methane inhibition was accompanied by a decrease in acetate and butyrate and an increase in propionate. At the highest concentration of microalgae (III), methane production was reduced by up to 70%. Total volatile fatty acid production was also significantly inhibited. Inhibition of total methane production was lower when incubated under 50% CO2 + 50% H2 than when incubated under 100% CO2. Increasing amounts of free DHA only showed a slight effect on the lipolysis of C18:2 c9c12 and had no apparent influence on the hydrogenation of C18:2 c9t11. The major inhibitory effect of free DHA appeared in the second hydrogenation step resulting in the accumulation of C18:1 t11. It is concluded that the addition of DHA-edible microalgae to in vitro incubations resulted to methane inhibition and incomplete hydrogenation of C18:2 c9c12 with the accumulation of C18: 1t11 which is comparable to in vitro effects of fish oil.