Changes in microbial community structure, methanogenesis and rumen fermentation in response to saponin-rich fractions from different plant materials.
OBJECTIVE
Investigation of the effects of saponin-rich fractions on rumen fermentation, methane production and the microbial community.


RESULTS
Saponins were extracted from Carduus, Sesbania and Knautia leaves and fenugreek seeds. Two levels of saponin-rich fractions with a substrate were incubated using the Hohenheim gas method. Methane was measured using an infrared-based methane analyser and microbial communities using quantitative PCR. On addition of saponin-rich fractions, methane and short-chain fatty acid production was not affected. The protozoal counts decreased by 10-39%. Sesbania saponins decreased methanogen population by 78%. Decrease in ruminal fungal population (20-60%) and increase in Fibrobacter succinogenes (21-45%) and Ruminococcus flavefaciens (23-40%) were observed.


CONCLUSIONS
The saponins evaluated possessed anti-protozoal activity; however, this activity did not lead to methane reduction. Fenugreek saponins seemed to have potential for increasing rumen efficiency. The saponins altered the microbial community towards proliferation of fibre-degrading bacteria and inhibition of fungal population.


CONCLUSIONS
The uni-directional relationship between protozoal numbers and methanogenesis, as affected by saponins, is not obligatory. All saponins might not hold promise for decreasing methane production from ruminants.
Goel
G
G
Institute for Animal Production in the Tropics and Subtropics (480b), University of Hohenheim, Stuttgart, Germany.
Makkar
H P S
HP
Becker
K
K
D000821:Animal Feed; D000818:Animals; D031177:Carduus; D002417:Cattle / Q000378:metabolism*; D049917:Dipsacaceae; D056890:Eukaryota / Q000302:isolation & purification; D005232:Fatty Acids, Volatile / Q000032:analysis; D005285:Fermentation; D008697:Methane / Q000032:analysis / Q000378:metabolism*; D010936:Plant Extracts / Q000008:administration & dosage*; D012417:Rumen / Q000378:metabolism / Q000382:microbiology*; D012503:Saponins / Q000008:administration & dosage*; D049931:Sesbania; D029910:Trigonella
D005232:Fatty Acids, Volatile; D010936:Plant Extracts; D012503:Saponins; C056164:fenugreek seed meal; D008697:Methane