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United States Department of Agriculture

Agricultural Research Service

Title: Leachate Conductivity As An Index for Quantifying Level of Forage Conditioning

Authors
item Kraus, Timothy - UNIVERSITY OF WISCONSIN
item Koegel, Richard
item Straub, Richard - UNIVERSITY OF WISCONSIN
item Shinners, Kevin - UNIVERSITY OF WISCONSIN

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 21, 1999
Publication Date: N/A

Interpretive Summary: Severe mechanical processing of forage crops, known as conditioning, has been shown to increase digestibility by cattle, thus increasing profitability. In order to benefit by this process, however, it is necessary to be able to measure the severity of the conditioning and to relate this to how much digestibility is increased. It was found that by washing the conditioned forage in a prescribed way and then measuring the electrical conductivity of the wash water (leachate), the extent of cell rupture could be determined. Plant chemistry which changes with environmental and other conditions can also affect conductivity, however. This problem was overcome by comparing the conductivity of leachate from conditioned forage with that of the same forage processed in a Waring blender. The latter process was found, by measuring chlorophyll release, to rupture an almost constant fraction of the plant cells. Thus, by comparing conductivities of the conditioned material with those of the blender treatment, it was possible to estimate the extent of cell rupture even though plant chemistry can vary widely with external conditions. Being able to measure extent of cell rupture simply and quickly allows evaluation of conditioning equipment as well as determination of what percent of plant cells must be ruptured to achieve the desired increase in forage digestibility. Such an increase will allow ruminant animal products to be produced more efficiently and profitably, as well as reducing the cost to consumers.

Technical Abstract: A method based upon measuring the conductivity of the leachate (LC) from mechanically conditioned forage was evaluated and used as an index for quantifying the extent of mechanical damage caused by various mechanical treatments. Relative to Surface Area Index (SAI) method previously used, the LC method was simple, fast, and could be completed with readily available laboratory equipment (orbital shaker table, Waringr blender, and conductivity meter). The LC method differentiated various mechanical conditioning treatments more often and with greater sensitivity than the SAI method. The consistency of different Waring blender treatments was assessed to determine if it could be used as a standard treatment for normalizing leachate conductivity values.

Last Modified: 12/22/2014
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