Abstract
The aim was to improve the rumen degradability of wheat straw (WS),
which has relatively high cell wall content. Plant cell walls consist of
hemicellulose and cellulose that are bound to lignin. These carbohydrates
can be an important source of energy for rumen microbes. However,
rumen microbes cannot degrade lignin, which blocks the availability of
the carbohydrates. The availability of carbohydrates can be increased
when lignin is removed in a pre-treatment. In nature, dead plants can
be degraded by fungi. Some fungal species degrade lignin without consuming
cellulose during vegetative growth. One of the selective lignin
degrading fungi, Lentinula edodes was used to test the improvement in
rumen degradability of WS. Two conditions were tested in triplicate:
autoclaved WS inoculated with L. edodes and autoclaved WS as control.
After 12 weeks of incubation at 24°C, rumen degradability was
determined with the in vitro gas production (IVGP) technique (Cone et
al., 1996). Lignin, hemicellulose and cellulose content were determined
according to the methods described by Van Soest et al. (1991). Changes
in chemical composition and IVGP upon fungal treatment were compared
with the control, using the generalized linear model method in
SAS (v9.3). To test the effect of changes in lignin structure and properties,
pyrolysis gas chromatography-mass spectrometry (py-GC/MS)
was done on fungal treated WS and the control. L. edodes treatment for
12 weeks increased (P <0.05) IVGP of WS compared with untreated
WS. Cellulose content was unchanged, while hemicellulose and lignin
content decreased (P <0.05). In addition to a decrease in total lignin,
py-GC/MS showed an increasing amount of lignin degradation products.
Upon L. edodes treatment not only a total degradation of lignin occurred,
but the composition of lignin also changed. Lignin in WS consists of
syringyl (S) and guaiacyl (G) units in a 1:1 ratio. L. edodes degraded
more S than G units, since the S/G ratio decreased. This decrease in
S/G ratio was correlated to an increase in IVGP. We conclude that the
L. edodes treatment increased the IVGP of WS, which was correlated
to both lignin content and composition.
| Original language | English |
|---|---|
| Title of host publication | Book of abstracts of 2015 Joint Annual Meeting of ADSA-ASAS |
| Pages | 605 |
| Volume | 98 |
| Publication status | Published - 2015 |
| Event | Joint Annual Meeting 2015 ADSA-ASAS - Orlando Duration: 12 Jul 2015 → 16 Jul 2015 |
Conference
| Conference | Joint Annual Meeting 2015 ADSA-ASAS |
|---|---|
| City | Orlando |
| Period | 12/07/15 → 16/07/15 |