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This article in CS

  1. Vol. 30 No. 5, p. 990-993
     
    Received: Nov 20, 1989


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doi:10.2135/cropsci1990.0011183X003000050006x

Relationship of Tissue Digestion to Textural Strength in Bermudagrass and Alfalfa Stems

  1. D. E. Akin ,
  2. L. L. Rigsby,
  3. C. E. Lyon and
  4. W. R. Windham
  1. Richard B. Russell Agric. Res. Ctr., USDA-ARS, P.O. Box 5677, Athens, GA 30613

Abstract

Abstract

Forage quality is determined to a large extent by the physical degradation of fiber and by exit of the digesta from the rumen. The effect of plant structure and prior microbial activity on the ease of physical breakdown, which occurs during chewing, is poorly defined. The objectives of this work were to identify structural characteristics primarily responsible for providing textural strength in stems and to relate this strength to tissue digestion by whole rumen fluid, by bacteria, or by fungi. The textural strength of stem residues was determined by applying force perpendicularly to the longitudinal axis of l-cm stem sections. Three-millimeters stem sections from the fourth and fifth internode of ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.] stems and from midway of stems of ‘120’ alfalfa (Medicago sativa L.) plants were incubated with the microbial groups or in control media for 72 h and compared for percentage area of tissue lost in cross sections or for the cross-sectional width of tissues remaining in stems. Rumen fluid and bacteria degraded substantial amounts of the stem parenchyma, but rumen fungi degraded significantly (P ≤ 0.05) lower amounts. None of the microbial groups removed the lignified ring tissues in either forage, and loss of other tissues within plants was similar for the microbial groups. Stems incubated with fungi were reduced the most in textural strength. Results indicated that the presence and integrity of the lignified ring was the primary structure responsible for strength in stem residues and that removal of parenchyma from stems under the conditions of this study was not a major factor affecting textural strength of stem residues.

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Copyright © 1990. Crop Science Society of America, Inc.Copyright © 1990 by the Crop Science Society of America, Inc.