Direct and indirect means of predicting forage quality through near infrared reflectance spectroscopy

The advent of NIRS technology for assessing quality of plant/forage/feed tissue and predicting diet quality from feces offers livestock nutritionists, researchers, farm advisors and resource consultants a rapid mechanism to acquire nutritional information. The portability and low long-term maintenance costs of this technology coupled with rapid turn around time on processing offers a mechanism for nutrition programs to address forage and dietary quality issues that were limited due to high maintenance costs of wet chemistry laboratories. The fundamentals of NIRS technology and associated development of calibration equations are discussed along with methods to validate equations. Direct methods for tissue analysis and indirect methods to predict diet quality from feces are reviewed for major constituents found in forages, including crude protein, digestibility, tannins and minerals.