Wet chemistry uses established laboratory tests to quantify protein, fiber, fat, and minerals. The minerals are smaller, thus more difficult to measure with the NIR. Wet chemistry should be used if precise levels are needed.
NIR (Near Infrared Reflectance spectroscopy) has been perfected to quickly, economically, and accurately measure nutrient content without destroying the sample. Also, NIR technology uses light reflectance and works best with large compounds such as those that make up protein and fiber. The NIR instrument must be calibrated to wet chemistry, which is the standard. Most typical forages can be analyzed with NIR, but unique forages may not be appropriately analyzed because no calibration set is available to standardize the equipment. Also, total mixed rations are sometimes difficult with NIR because the composition of the mix can vary greatly from farm to farm.