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This article in CS

  1. Vol. 21 No. 3, p. 355-358
     
    Received: Apr 17, 1980


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doi:10.2135/cropsci1981.0011183X002100030001x

Description and Evaluation of a near Infrared Reflectance Spectro-Computer for Forage and Grain Analysis1

  1. J. S. Shenk,
  2. I. Landa,
  3. M. R. Hoover and
  4. M. O. Westerhaus2

Abstract

Abstract

Near infrared (NIR) reflectance has been proposed as a procedure to determine the nutritive value of forages and feedstuffs. A Neotec model 6100 scanning monochromator interfaced to a PDP-11 minicomputer was used for this study. Instruments of this type are called spectro-computers. Ten computer programs developed at University Park, Penn. were used to operate and test the instrument. The scanning range of the spectro-computer was from 1,100 to 2,500 nm. Wavelength accuracy was ± 1.0nm, wavelength precision ± 0.01 nm, stray light <0.10%, and system peak to peak and root mean square noises were 0.33 × 10-3 and 0.05 × 10-3, respectively, expressed as log (1/R). This high level of monochromator performance permits the spectro-computer precision to compare favorably with that of the standard laboratory procedures.

Two hundred forage samples were used to test the accuracy of the spectro-computer system. These samples represented a broad array of species and mixtures, stages of maturity, and harvest locations. Protein and in vitro dry matter disappearance were predicted best with NIR data treated as log of 1/R, resulting in standard errors of prediction of 0.96 and 3.18%, respectively. Other quality parameters were predicted better when the log (1/R) NIR data were transformed to the second derivative. They were acid detergent fiber ± 1.99%, neutral detergent fiber ± 2.27%, lignin ± 1.13%, cellulose ± 1.27%, Ca ± 0.16%, P ± 0.04%, and K ± 0.37%.Further study of the prediction of protein in 90 Canadian wheat (Triticum aestivum L.) samples resulted in a prediction error of 0.17%. We believe this spectro-computer system is suitable for use in forage and grain analysis.

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