| Summary: | High ingredient costs and a competitive market have promoted support for
research by the feed industry to improve the utilization of protein and energy
feedstuffs such as barley and canola meal. The objective of this research was to
determine the feasibility of using enzyme and mild hydrothermal treatment to
improve the nutritional value of barley grain and canola meal for use by dairy cattle.
In experiment 1, barley which was subjected to p - glucanase , protease and xylanase
enzymes and mild hydrothermal treatment, was evaluated using 48 h in vitro dry
matter disappearance ( IVDMD ) , in vitro true digestibility (IVTD), acid detergent fiber
(ADF) and neutral detergent fiber (NDF) analyses . A number of interactions (P <
0.05) were observed for the digestibility parameters. Results of fiber analyses were
inconclusive . Overall , the addition of xylanase was found to be detrimental and the
mild hydrothermal treatment did not have an effect on enzyme activity. The addition
of protease and / or p - glucanase to barley suggest potential application that may be
further investigated. In experiment 2, canola meal was subjected to protease,
xylanase enzymes and mild hydrothermal treatment. Treatments were evaluated
using IVDMD, IVTD, ADF and NDF . Significant interactions (P < 0.05) were
observed for IVDMD , IVTD, ADF and NDF. The addition of moisture significantly
increased (P < 0.05) IVDMD and IVTD. Protease also elicited an effect (P < 0.05) on
the NDF content. From this experiment, similar conclusions to those in experiment 1
were drawn: neither xylanase nor mild heat treatment was effective in improving
digestibility. However, the addition of protease to canola meal at an intermediate
level of application improved it's digestibility significantly (P < 0.05). Fiber analyses
resulted in a large number of interactions which produced variable responses .
Experiment 3 evaluated the effects of the treatments on the fermentation
characteristics of canola meal using the in vitro gas production technique. Rate of
gas production was significantly (P < 0.05) affected by protease, wheras , the
length of the lag phase was significantly affected by the interaction between
protease and xylanase (P < 0.05). In general , the treatments increased rate and
decreased lag time. Volatile fatty acid (VFA) analyses revealed a significant
interaction (P < 0.05) between protease and xylanase . There was a positive linear/
relationship (P < 0.05) between the level of protease application and the ratio of
acetate to propionate. Protease also had an effect (P < 0.05) on the ratio of butyrate
to propionate. Xylanase also significantly (P < 0.05) both acetate and butyrate
production relative to propionate. Results from experiment 3 indicated the
application of protease at higher levels was beneficial in terms of improving the
nutritional value of canola meal . From the work conducted in this thesis , it may be
concluded , in the case of both barley and canola meal, that xylanase was
detrimental to digestibility and that mild hydrothermal treatment did not improve
enzyme activities. Many enzyme treatments increased the proportion of fiber,
suggesting a shift in feed composition . The results of this study suggest potential
applications of the treatment of barley with protease or a combination of protease
and p - glucanase enzymes . Treatment of canola meal with protease between the
levels of 0 . 0 1% and 0 . 0 5% (vol / wt) resulted in the greatest improvement in it's
nutritive value for dairy cattle. The in vitro work presented in this thesis
demonstrates the potential improvements with enzyme technology in the feeding
quality of barley and canola meal fed to dairy cattle.
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