Sally A. Flis, Ph.D. – Feed and Crop Support Specialist, Dairy One –

In the February blog post, I talked about the change from aNDF to aNDFom, but I forgot to talk about why the “a” was added to your NDF. Starting in January, all of the Forage Lab reports had NDF reported as aNDF.

The NDF analysis was introduced in the 1960s to describe the total fiber content of feed, collectively the hemicellulose, cellulose, and lignin. The dried and ground sample is boiled in NDF solution for an hour to remove the unwanted nutrients, leaving the fiber residue behind. Various reagents are included in the solution to wash out the protein, fat, starch, etc. and leave the fibrous residue behind.

Chemicals in Neutral Detergent (ND) solution to dissolve the unwanted nutrients:
Sodium dodecyl sulfate – protein & fats
EDTA (ethylene diamine tetra acetic acid) – Ca, Mg, Zn, pectins
Triethylene glycol – starch
Sodium borate – buffer
Sodium phosphate dibasic – buffer

NDF chem

Neutral Detergent Fiber Analysis: From L to R – Neutral detergent solution concentrate (mixed in the lab with water), Sodium sulfite (added to each run), Triethylene glycol (added to each run), and Alpha amylase (brown, added to each run).

In the 1990s, amylase and sodium sulfite were added to the ND solution to further clean up the residue and give a more accurate representation of fiber in the sample. Amylase was added to help breakdown the starch. Sodium sulfite was added to help remove protein.

ndf steps

NDF Analysis steps: From L to R – Forage as received by the lab, dried and ground sample, and fiber that remains on a filter paper after an NDF analysis.

Until this year, labs have reported all NDF analysis as NDF. Some labs are not using the amylase, and some are. With the addition of “om” for the ash correction,  the forage analysis community decided to add the “a” to NDF so that customers could be sure of the analysis used on their samples. The use of amylase is the official procedure and we have always used amylase and sodium sulfite in our analysis. So, your NDF and aNDF are the same thing; it’s just the name that is new.

If you have any questions on your feed or forage analysis, please contact me at, or the forage lab via e-mail at or via phone at 1-800-344-2697 ext. 2172.