SR-FTIR Microspectroscopy as a Tool for Evaluating the Digestibility Characteristics of Cereal Grains Fed to Ruminants

by Walker, Amanda

Abstract (Summary)
Dry matter, crude protein and starch degradation characteristics of one corn (Pioneer 39P78) and four barley grain varieties (CDC Bold, CDC Dolly, Harrington and Valier) were evaluated in two in situ nylon bag trials. Trial 1 compared ground and rolled treatments of Harrington barley and Pioneer 39P78 corn, whereas Trial 2 evaluated ground and rolled treatments of the four barley varieties. Rumen degradability characteristics were compared with analytical results from thermal- and synchrotron-source FTIRM. Infrared absorbance spectra were collected from corn and four barley varieties using thermal-source FTIRM on the mid-IR beamline at the Canadian Light Source, Ltd. (Saskatoon, SK). Synchrotron-source FTIRM spectral data was collected for corn, Harrington barley and Valier barley on the U2B mid-IR beamline at NSLS-BNL (Upton, NY). CHO:Amide I peak area ratios were compared to the in situ rumen degradation results to determine if FTIRM spectral data could be related to the rate and extent of rumen degradation, and if thermal- and synchrotron-source FTIRM yielded different results. A grain x processing method interaction (P<0.01) was observed in both in situ trials where grinding produced a greater increase in the rate and extent of rumen degradation for Harrington barley than it did for corn (Trial 1) along with a greater increase in the rate and extent of rumen degradation for CDC Bold and CDC Dolly than for Harrington and Valier (Trial 2). Among barley varieties, increasing rate and extent of rumen degradation (CDC Bold>CDC Dolly>Harrington>Valier) corresponded to increasing starch:protein ratio as estimated by chemical analysis. This relationship was reversed for corn and Harrington barley where corn had a higher starch:protein ratio yet slower rumen degradation kinetics. For both thermal- and synchrotron-source FTIRM, CHO:amide I peak area ratios were greater (P<0.05) for corn than for Harrington barley. Comparison of CHO:amide I peak area ratios of barley varieties measured with thermal-source FTIR showed that varieties with higher (P<0.05) CHO:Amide I peak area ratios generally had higher rate and extent of rumen degradation. This indicates that starch:protein ratio estimated with FTIRM may be an indicator of rumen degradability characteristics when comparing varieties of the same grain, but not for different species of grains.
Bibliographical Information:

Advisor:Yu, Peiqiang; McKinnon, John J.; Christensen, David A.; Christensen, Colleen R.; Buchanan, Fiona C.

School:University of Saskatchewan

School Location:Canada - Saskatchewan

Source Type:Master's Thesis

Keywords:infrared microspectroscopy synchrotron rumen degradability barley


Date of Publication:05/14/2007

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