Author
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Reeves Iii, James |
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Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/16/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Mid-infrared spectroscopy is a non-destructive assay method using a form of light which can be used to determine the composition and quality of materials. Treating materials such as straw and other byproducts has been carried out for many years in an effort to increase their digestibility by ruminants, and therefore their economic value. The objective of this study ywas to determine the advantages and disadvantages of mid-infrared diffuse reflectance spectroscopy versus near-infrared for the qualitative analysis of diversely treated feedstuffs. Study samples (325) were selected from 2808 possible sample-treatment combinations. Neutral detergent fiber and crude protein were determined on all samples and calculated on an organic dry matter basis. Samples were scanned in the mid- and near-infrared (Different type of light. The results obtained showed that: 1. Visual determination of likely compositional or spectral outliers (samples whose interaction with the mid-infrared light is very different from that of the majority of the samples) is not obviously feasible using either mid- or near-infrared spectra. 2. Changes in spectra (graphical representation of how the light and sample interact) due to treatment can be much more easily attributed to compositional components using mid- as opposed to near- infrared spectra. And 3, Examination of either mid-infrared PLS or PCR factors (graphical displays resulting from statistical analysis using the spectra in question) can be useful in determining compositional changes caused by treatments, while near-infrared PLS and PCR factors appear to be dominated by moisture differences in the samples. In conclusion, mid- infrared spectra appear to be more useful in determining the effects of treatments on forages and byproducts. Technical Abstract: The objective of this study was to determine the advantages and disadvantages of mid-infrared diffuse reflectance spectroscopy versus near-infrared for the qualitative analysis of diversely treated forages and by-products. Study samples (325) were randomly selected from 2808 possible sample-treatment combinations generated using eighteen feedstuffs, 26 treatments (acids, bases, oxidizing and reducing agents, heat, etc.), and six levels of reagent for each treatment. Neutral detergent fiber and crude protein were determined on all samples and calculated on an organic dry matter basis. Samples were scanned (256 scans each) from 4000 to 400 cm-1 at 4 and 16 cm-1 resolutions on a Fourier transform infrared spectrometer equipped with a sample transport device, and in the near-infrared using a scanning monochromator. The results obtained showed that: 1. Visual determination of likely compositional or spectral outliers is not obviously feasible using either mid- or near-infrared spectra. 2. Changes in spectra due to treatment can be much more easily attributed to compositional components using mid- as opposed to near-infrared spectra. And 3, Examination of either mid-infrared PLS or PCR factors can be useful in determining compositional changes caused by treatments, while near-infrared PLS and PCR factors appear to be dominated by moisture differences. |
