A computer-based system for characterizing in real time the nutritional components of one of more ingredients for a ruminant feed ration, including dry matter, NDF, NDFd, lignified NDF ratio, peNDF, percent starch, IVSD, and particle size for a forage material; and IVSD and particle size for a grain material. The system utilizes proprietary NIRS equations based upon prior samplings of a variety of crop species like dual-purpose corn silage, leafy corn silage, brown midrib (“BMR”) corn silage, grass (silage/dry), alfalfa (silage/dry), BMR forage sorghum, normal dent starch grain, floury endosperm starch grain, vitreous endosperm grain, and steam-flaked corn grain, and applies those equations to current samplings of a corresponding crop to predict in real time the characteristics of such forage or grain material. The real-time characterization system may also utilize the predicted data to calculate a “total ration fermentation index” value that takes into account the total NDFd and IVSD characteristics (including RAS and RBS) of the forage and starch ingredients to be used in a feed ration to ensure that the ration will not contribute too much or too little digestibility to the cow. A “flash fermentation index” identifies feed formulations, based upon the real-time characterizations of the ingredients, that are too “hot” to feed to the cows without incurring the risk of lost production and adverse health issues.