Title: Diffuse Reflectance Fourier Transform Mid-Infrared Spectral Properties of Forages with Varied Fatty Acid Content Authors
|Reeves Iii, James|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 25, 2007
Publication Date: October 18, 2007
Citation: Calderon, F.J., Reeves Iii, J.B., Foster, J.G., Clapham, W.M., Fedders, J.M., Vigil, M.F., Henry, W.B. 2007. Diffuse Reflectance Fourier Transform Mid-Infrared Spectral Properties of Forages with Varied Fatty Acid Content. Meeting Abstract. Presented at the 2007 National Federation of Analytical Chemistry and Spectroscopy Societies annual meeting. Oct. 14-18, 2007. Memphis, TN. Technical Abstract: Ruminant diet can affect the fatty acid (FA) content of meat and dairy products, which indicates that managing forage consumption is important in determining the quality of the animal products. Mid-infrared spectroscopy is sensitive to changes in forage FA and has been used successfully to quantify FA in forages using chemometrics. However, few studies have attempted to identify the specific spectral changes that occur due to fatty acid variability in plant materials low in lipid content, where spectral differences may be subtle. A total of 182 samples from eleven forage species, including 13 varieties, were sampled at three growth stages. Samples were scanned using Fourier transform mid-infrared spectroscopy (FTMIR) and analyzed by gas chromatography for lauric, myristic, palmitic, stearic, palmitoleic, oleic, linoleic, and alpha-linolenic acids. Principal components analysis shows that forbs, legumes and grasses form separate clusters according to their fatty acid profiles. Grasses have low C18:0 and high C14:1 relative to the other forage types. Forbs have relatively low amounts of C18:2 and C 14:1, and high amounts of C 14:0. Forage samples from the first harvest tend to have high C16:0, C16:1 and C18:3, but lower C14:1. The principal components analysis of the FTMIR spectra shows that there was a clear separation between the spectra from the first harvest and those of the last two harvests because absorbances in 3320-3615 cm-1, 3245 cm-1, 2892 cm-1, and 1150-1170 cm-1 increased with harvest time. Partial least squares analysis showed that bands at 1678 cm-1, 1536 cm-1, 1397 cm-1, 825 cm-1, and 536 cm-1 were positively correlated with C16:0, C16:1 and C18:2 concentration in forages, while a wide band at 3501 cm-1 was negatively correlated.