This experiment was conducted to investigate the effect of coconut oil and garlic powder
supplementation on digestibility of nutrients, rumen fermentation, rumen ecology, rumen
microorganism and methanogen diversity. Four, 3-year old, rumen fistulated swamp buffalo
bulls were randomly assigned in a 4×4 Latin square design to receive four dietary treatments;
7% coconut oil, 7% coconut oil with 50 g/day of garlic powder, 7% coconut oil with 100 g/day of
garlic powder and non-supplemented (control). During the experiment, concentrate was
offered at 0.5% of BW while rice straw was given on ad libitum basis. It was found that
supplementation of 7% coconut oil had significantly influenced on total DM intake, OM, NDF
and ADF digestibilites while supplementation of 7% coconut oil with garlic powder (50 and
100 g/day) were not significantly different when compared with the control. Dietary
supplementations did not affect on rumen pH, NH3–N concentrations. Blood urea nitrogen
(BUN) was significantly higher in supplemented groups. Total VFA concentration, proportion of
acetate and acetate to propionate ratio were reduced by supplementation. Proportion of
propionate was increased (Pb0.05) when supplemented with 7% coconut oil and 7% coconut oil
with 100 g/day of garlic powder. Methane production was dramatically reduced (P=0.005) in
supplemented treatments and was 10% reduced in 7% coconut oil supplementation. Amylolytic
and proteolytic bacteria were increased (P=0.007 and P=0.024) while protozoal population
decreased by 68–75% (Pb0.01) by supplementation. Total bacterial population was increased
by supplementation while total fungi and total methanogens were not significantly different
among treatments. Percentage of cellulolytic bacterial population was not different among
treatments. However, dietary supplementation reduced (P b0.001) percentage of F.
succinogenes population. However, methanogen diversity was not changed using PCR–DGGE
as technique. Thirteen separate bands were found in the DGGE gel. Based on this study,
supplementation with 7% coconut oil plus 100 g/day of garlic powder could be efficiently
utilized in the rumen and thus, could provide good fermentation end products and improve
rumen ecology for the host swamp buffaloes particularly in reducing 9% methane gas
production without changing nutrient digestibilities.