We couple that with the cow's intake, which tells us how long she'll hang onto the forage. This gives us an estimate of the energy value of that particular forage for a cow at a particular level of production. When Combs used the new and old equations on forage samples from Wisconsin labs, he got different results with about 30 percent of the samples. Subsamples run through lab and rumen tests showed that digestion kinetics predictions were more accurate than predictions from the old equations. Most labs analyze forages using near-infrared reflectance spectroscopy, because it's cheap and quick.
Wet chemistry takes longer and costs more.
Combs plans further validations and feeding trials to compare the old and new systems. He's also working with other CALS dairy scientists to incorporate the new system into current UW ration software. The test will be available at forage testing labs by the end of March. CALS dairy scientists work with a consortium of NIRS labs in the upper Midwest. Combs hopes to release these equations through the consortium, where they can be downloaded to anyone's NIR machine.