Forages,
including maize (Zea mays L.) silage,
are key components of diets for ruminants. There is a renewed interest in
forages especially in energy dense diets such as those required for high
producing dairy cows due to the increase in grain prices partially driven by
the creation of new markets especially for corn grain as a primary feedstock
for ethanol production.
The cross-linked
nature of plant cell walls provides structural integrity for continued growth
and development, but limits degradation and utilization by ruminants. In
grasses, a major cross-linking component is ferulic acid that is incorporated
into cell walls as an ester linked residue on arabinoxylans. Ferulates can
become coupled to each other and to lignin forming a highly cross-linked
matrix of carbohydrates and lignin. Seedling ferulate ester mutants (sfe)
were produced in maize using the transposon system and evaluated in feeding
trials. The work described here was undertaken to characterize changes in the
ferulate cross-linked nature as well as other components of the corn cell wall
matrix in leaf, sheath and stem tissues.
Near-isogenic lines
of the putative sfe maize mutant were
compared to the parental inbred W23 to determine cell wall characteristics. Two sfe lines (W23sfe4 and W23sfe21 independent mutant lines) were chosen for study. Equal amounts of dried and ground material from each field plot,
location, and year (N = 16) for every maize line was combined to create
individual leaf blade, sheath, and stem samples of W23, W23sfe4, and W23sfe21.
The results showed that
total ferulates decreased modestly due to the mutation and were more
apparent in leaf tissue (16% - 18%) compared to sheath (+5
to -6% change) and stem (8% - 9% decrease). The most significant
changes were in the ether linked ferulates to lignin, both monomer and
dehydrodiferulates (14% to 38% decrease). Other characteristics of the
cell wall (lignin, neutral sugar composition) also showed modest changes. The
change in total ferulates was modest, but led to improved animal performance.
In short, these
findings suggest that relatively small changes can have an additive effect
resulting in improved animal performance without the need for large shifts in
cell wall composition.
Article by Ronald
D. Hatfield, et al, from USA.
Full access: http://mrw.so/4n9cwb
Image by wenxue2222, from Flickr-cc.
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