Forage fermentation by bacteria
As the concentration of bacteria increased, the rate of gas production was
increased. Maximal gas production was attained, using either substrate, with
BFRF plus bacteria resuspended in 0.1 of the original volume (Fig. 2 ). Total
VFA concentration was increased with increasing bacterial density (Table 2 ),
both with hay and with barley straw. The proportions of acetate:
propionate: butyrate were not significantly different (P> 0.05 ) between
treatments, whether incubated with hay or with barley straw. The net gas production
from barley straw was significantly higher (P< 0.05 ) when the bacterial
density was increased from the original density to higher densities.
However, net gas production from hay by bacteria resuspended in 0.067 of
the original volume was significantly lower than that by bacteria resuspended
in either 0.1 or 0.2 of the original volume (P< 0.05 ).
The addition of protozoa to a suspension of rumen bacteria resuspended in
0.1 of the original volume did not affect the rate of gas production by the
bacterial suspension, whether incubated with hay or with barley straw (Fig.
3 ). Similarly, the addition of protozoa had no significant effect on either the
total VFA production or the proportions of VFA produced from either hay or
barley straw (Table 3 ).