Microbial Degradation of Smooth Brome and Tall Fescue Observed by Scanning Electron Microscopy2

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Abstract
A scanning electron microscope was used to observe Bromus inermis (smooth brome) and Festuca arundinacea (tall fescue) before and after degradation in the rumen. X-ray dispersion of silicon showed it to be localized in adaxial epidermal cells above vascular bundles and in every abaxial epidermal cell of both grasses. Digestive patterns were similar for both grasses. Mesophyll was rapidly degraded, followed by slow hydrolysis of bundle sheath cells and sclerenchymal tissue. Ruptured adaxial and intact abaxial cuticle and vascular tissue remained after 72 hr digestion. Rate of digestion was initially higher in brome than in fescue, but it was similar by 48 hours. Silica and cuticle impose a barrier to microbial penetration of leaf tissue. Lignin prevents digestion of vascular tissue and slows hydrolysis of schlerenchymal and epidermal tissues. Copyright © 1980. American Society of Animal Science . Copyright 1980 by American Society of Animal Science