Increasing the EFE dose resulted in increased preingestive
fiber hydrolysis of BH, as well as increases
in in vitro digestion and fermentation, but the extent
and nature of the responses differed with the EFE and
dose. These results indicate that EFE doses can be manipulated
to increase preingestive fiber hydrolysis and
digestion, which might increase the supply of nutrients
to lactating cows fed enzyme-treated BH. In particular,
the consistent increase in sugar release as doses of
each of the EFE increased implies increased supply of
highly available substrates for rumen microorganisms.
The highest EFE doses were consistently the most
effective at increasing NDF and HEM hydrolysis and
releasing WSC, but they were not the most effective at
increasing in vitro digestibility or fermentation. This
indicates that using measures of preingestive hydrolysis,
such as release of WSC, to choose doses that will
increase animal responses will probably be misleading.
Baseline EFE doses examined in the current study
were recommended by the manufacturers such that
some EFE were applied at higher doses than others.
Based on their ability to increase NDFD, EFE with
lower baseline manufacturer-stipulated doses (1A and
2A) benefited from increasing the dose, whereas those
with greater baseline doses (13D and 15D) benefited
from reducing the dose. Consequently the optimal dose
for the former was 2× the baseline dose, whereas that
for the latter was 0.5× the baseline dose. The best dose
for EFE 11C, which had an intermediate baseline dose,
was the manufacturer-stipulated dose. Dose rates that
enhanced digestibility also typically increased fermentation
product concentrations and reduced the A:P
ratio, and hence increased energetic efficiency.