Using Near Infrared Reflectance Spectroscopy to Estimate In Vitro True Digestibility of Coastal Bermudagrass.

The objective of this study was to develop near infrared reflectance spectroscopy (NIRS) calibration to predict in vitro true digestibility (IVTD) of Coastal bermudagrass. Approximately 200 Coastal bermudagrass samples of varying maturity and quality were obtained and subject to Ankom IVTD analysis using a Daisy II incubator and 48 hour period.  Each sample was analyzed in duplicate or greater within each batch of rumen fluid, and among at least two separate fluids.  Samples were also analyzed for crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Based on these results, 101 samples ranging from 49.5 – 88.4 percent IVTD were selected for NIR analysis.  The samples were scanned in triplicates, three repacks in a cell, using a Unity Scientific SpectraStar 2500 NIR Analyzer. The average of the three scans was imported into the Unity Scientific CalStar and UCal calibration software programs. Various models or calibrations were developed and tested using the original 101 sample data and the other 99 samples not included in the calibration set. The R² statistic from the software for the calibrations ranged from .77 to .92. Based on this research, it is apparent that NIRS can be calibrated to predict IVTD on Coastal bermudagrass.  Future research should focus on making IVTD calibrations more universal among laboratories, as well as utilizing IVTD values to predict available energy in forages.