NIR Feed and Forage Analysis
There are two main methods for the analysis of feeds and forages: Near Infrared Reflectance (NIR) and wet chemical analysis. Each method has advantages and disadvantages. Weld Laboratories is one of only 24 laboratories certified by the National Forage Testing Association (NFTA) in both NIR and chemical analyses. Over the past ten years, substantial improvements have been made in NIR technology, and it has become an important tool in the evaluation of forages.

NIR Analysis of Feed and Forage Materials

NIR stands for Near Infrared Reflectance. A finely ground sample of feed material is prepared, and the NIR instrument exposes this material to near infrared energy. The energy or light which is reflected is matched by the computer to a database of know samples. The computer assigns the values to the various feed components in the sample and prepares the report. As such, NIR is an indirect determination.

Sample NIR report

Advantages of NIR Analysis

The NIR method is much faster and less expensive than wet chemical analysis. The sample must be dried to below four percent moisture, ground, and analyzed by the NIR instrument. Sample drying is the slowest step, and the entire process usually takes less than 24 hours. High moisture samples such as corn silages and haylages typically are completed in 48 hours due to the longer drying times.

The NIR method generally gives good results for alfalfa, grass hay, mixtures of alfalfa and grass hay, haylages, corn silage, grains, and small grain silages.

Disadvantages of NIR Analysis

  • The presence of weeds or other plant or organic material will adversely affect the analysis.
  • The values obtained for minerals in the NIR method are, at best, good estimates.
  • Dirt or mineral supplements are not detected by NIR analysis.
  • Mixtures of different feed materials often give poor results.

No NIR Match or Poor NIR Match

Mixed samples of different feed materials, samples containing large quantities of weeds, some range forages, and forages which have been cut and then exposed to rain often do not give good NIR results. That is, the sample does not match up with the NIR database. If these samples are close to the database we will stamp the report "Poor NIR Match". We do not report the results of samples which have a large variance from the NIR database. For these samples, we suggest chemical analysis, and we do not charge for the NIR analysis.

Dairy Quality Alfalfa

Dairy cows milk best on forages which have a high Relative Feed Value (RFV). These would be premium alfalfas which are low in acid detergent and neutral detergent fibers (ADF and NDF). There is no universal value for diary quality alfalfas; however, the lower end of the range appears to be near 160 RFV.

NIR Advances

Basic NIR report and calculations are those which have been in use for a number of years. Recently the NIRS Consortium developed additional equations to the basic NIR packages. Relative Forage Quality (RFQ) is a measure of how digestible the forage material is. A sample which has an RFV of 160 and an RFQ of 180 would be considered more digestible than a sample with an RFV of 160 and RFQ of 150.

There is also a Consortium equation for corn silages that provides lignin, ash, fat, and dNDF48. This equation calculates TDN and NEL using the Weiss equation rather than basing calculations on ADF alone.

Costs

Basic NIR Packages $15 (alfalfa and grass hays, haylage, corn silage, grains, and small grain silages)

Relative Forage Quality $17 (alfalfa and grass hays)

Corn Silage Premium $17 (corn silage package with lignin, ash, fat, and dNDF48)

Basic NIR plus Calcium, Phosphorus, Magnesium, and Potassium by wet chemistry $35