Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/1998
Publication Date: N/A
Citation: 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 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 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 improvement in digestibility. Improved digestibility can lead to improved profitability for the producer and decreased prices for the consumer of ruminant animal products.
Technical Abstract: Research was conducted to develop a method to normalize leachate conductivity values with respect to changes in plant chemistry so that values could be compared across a wide variety of crop conditions. The consistency of various Waring blender treatments was assessed by measuring the amount of chlorophyll leached from ruptured cells as a fraction of total chlorophyll in a sample. The extent of cellular rupture remained nearly constant across a wide variety of crop conditions when forage samples were conditioned using a Waring blender for 1 and 2 min with blender speeds of approximately 18,000 and 22,000 r/min, respectively. Blending times exceeding 2 min increased the mixture temperature beyond a critical level causing proteins to coagulate. A standard method for normalizing leachate conductivity values is given.