For
more information contact Mike Rankin
Mike Rankin
Crops and Soils Agent - Fond du Lac County
University of Wisconsin - Extension
Forage testing using near infrared reflectance spectroscopy (NIR) is a valuable but often misunderstood forage testing tool. The accuracy of NIR depends on a number of factors. These include: a representative sample being taken, proper handling of the sample between the time it is taken and the time of testing, the testing lab using the most comprehensive calibration equations currently available, and constant monitoring of NIR results with that of a standard method.
With all of the above criteria in place, the accuracy of NIR results is still highly dependent on the quality parameter being measured. A general ranking of accuracy is presented in the table below:
| Accuracy of NIR in Predicting Forage Quality Parameters | |
| Parameter | Relative Accuracy |
| Dry Matter | Excellent |
| Crude Protein | Excellent |
| ADF | Excellent |
| NDF | Excellent |
| UIP | Good |
| Soluble CP | Good |
| Calcium | Good |
| ADF – CP | Fair |
| NDF – CP | Fair |
| Phosphorus | Poor |
| Potassium | Poor |
| Magnesium | Poor |
Armed with the above information, producers and consultants can be reasonably confidant of NIR results when measuring certain protein, fiber, and calcium components. Conversely, NIR readings for heat-damaged protein, phosphorus, potassium, and magnesium are highly questionable and probably should not even be included on the analysis.
For
more information contact Mike Rankin