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Crop Science Abstract -

Prediction of Leaf Fraction, Neutral Detergent Fiber, and Intake of Ground Forage Samples by Airflow Segregation1


This article in CS

  1. Vol. 27 No. 3, p. 601-603
    Received: Apr 21, 1986

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  1. Kanneganti V. Rao,
  2. P. J. Van Soest and
  3. G. W. Fick2



Research on forage nutritional quality is facilitated by procedures that are fast and simple and that require only small samples. This is especially true for dry matter intake, which can now be accurately evaluated only by feeding trials. In order to evaluate airflow segregation as a method of forage analysis, oven dried forage samples, ground to pass a 2-mm screen, were separated into coarse and fine portions using several airflow speeds in a seed cleaner. An airflow speed setting of 7 units gave the cleanest separation of leaf from stem material, but contamination of the coarse portion with leaf fragments and of the fine portion with stem fragments could be easily seen at 4✕ magnification. However, for alfalfa (Medicago sativa L.), actual leaflet fraction of the original herbage regressed on coarse portion of the separated material gave the equation Y = 1.669 – 2.665 . X, n = 25,r2 = 0.99, and a root error mean square of 0.024. Neutral detergent fiber (NDF) and intake of alfalfa herbage were highly correlated to the coarse portion (r = 0.85 and -0.87, respectively), but this was not true when other forage species were considered. Airflow separation can be calibrated to predict leaf and NDF fractions of pure alfalfa samples, but a universal relationship was not found across a range of temperate forages.

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