Procedures for processing cattle fecal samples for NIRS analysis

Abstract

Factors related to and methods for processing cattle fecal samples for rapid analysis with near-IR reflectance spectroscopy (NIRS) for forage diet quality predictions were investigated. No differences ( P < 0.05) were found between mean prediction values for crude protein (CP) and 48-h in vitro digestible organic matter (IVDOM) for 1 and 4 h periods post-grinding. Sample hydration status, however, had a marked effect on predictions for both CP and IVDOM, indicating the necessity for control of sample moisture to obtain rapid and accurate analyses. Predictions for both CP and IV-DOM for microwave dried (MW) and forced-air oven dried (OD) samples were only slightly different in magnitude but differences were statistically significant using calibration equations developed from OD samples. These differences suggested the need for MW calibrations. Procedures for microwave drying and combined microwave and forced-air oven drying of cattle fecal samples were developed which resulted in NIRS calibrations which were statistically equivalent to calibrations with samples which had been dried in a forced-air oven.