Validation of the Combs-Goeser in vitro procedure to test if it improves repeatability and precision of neutral detergent fiber (NDF) digestibility measurements to allow improved near-infrared reflectance spectroscopy (NIRS) calibration

Abstract

Abstract: More precise and accurate estimates of NDF digestibility (NDFD) are needed to better predict forage energy utilization by dairy cattle. Currently, NDFD measurement accuracy and repeatability are weak due to two facets, lab-to-lab variability and run-to-run variability, making it a poor tool for feed formulation. The objective of this research was to validate the Combs-Goeser in vitro fiber digestion procedure that was developed and the concurrent Near-Infrared Reflectance Spectroscopy (NIRS) calibration that is based upon the wet data from this procedure. I hypothesize that the new in vitro method will significantly reduce variation in measurement of NDFD, and this will allow improved NIRS calibration. This new procedure and concurrent NIRS calibration was validated against the in vitro procedures and calibrated NIRS procedures currently used by major commercial forage testing laboratories. A more precise and repeatable NDFD procedure would have great impact on the dairy industry in Wisconsin and the Midwest by allowing nutritionists and producers to more accurately predict forage digestion and ultimately milk production from forage crops.