This study characterizes the effects of concentrated
pomegranate-peel extract (CPE) addition to the TMR
at levels of 1, 2, or 4% on voluntary intake, in vivo
digestibility, milk yield and composition, and profile of
rumen bacterial and archaeal populations in lactating
Holstein cows. Supplementation of CPE significantly
affected the abundance of methanogenic archaea and
specific ruminal bacterial species related to cellulolytic
activities and soluble sugar and lactic acid fermentation,
as revealed by real-time PCR quantification.
Furthermore, CPE supplementation had a significant
dose-dependent effect on the whole ruminal bacterial
community, as determined by automated ribosomal
intergenic spacer analysis. These changes were accompanied
by a significant increase in digestibility of dry
matter, crude protein, and neutral detergent fiber, as
well as milk and energy-corrected milk yields in cows
fed the 4% CPE supplement. These results suggest that
CPE supplementation significantly affects the rumen
bacterial communities, which in turn may be related to
a beneficial effect on dairy cow performance.