Testing forages gives you answers when it comes to utilization, but what test is right for your operation?
The two primary components that any forage test needs to supply are a measure of energy and protein content. Energy is usually measured in total digestible nutrients (TDN) and protein is labeled as is, or crude protein (CP). Because moisture content of samples can vary widely, the focus of the results should be on the dry matter basis. Most lab analysis will provide these measures in a basic forage analysis package.
In certain circumstances, producers may test for key minerals or nitrates. A mineral package may not be required for every sample submitted, but can be crucial. In cases where minerals are oversupplied, a custom mineral supplement may omit the unneeded mineral, saving cost. Both over and undersupplied key minerals can cause a host of production and reproductive issues that knowing about, we can plan ahead to address. Stressed plants, especially annual crops, have the potential to accumulate high levels of nitrate, so running an additional nitrate test on these species is crucial.
Finally, what type of test needs to be completed? In some labs, wet chemistry tests are the only option. These are the traditional method for determining nutrient levels and are arguably the most accurate option available, especially for mineral analysis. However, may labs have begun offering near-infrared spectrometry (NIRS). These tests use a laser to “read” the sample and compare it to a databank of known similar samples built upon regression calibration that can approximate wet chemistry tests quickly and cheaply. NIRS works best with single species samples and is more accurate with popular forages.
Ultimately, which test you choose depends on number of samples, cost, species and ability of labs to test samples. NIRS would work well if you were testing many samples, needed quick results, and a pure stand of a popular forage, like alfalfa. Wet chemistry would work well if you had fewer samples, were testing for minerals, and were working with a more novel forage.