Cumberland Valley Analytical Services has recently added the unique ability to provide several key nutrient evaluations of forages by near-infared spectroscopy (NIR). These include total fatty acids, indigestible fiber, and soluble fiber. Forage categories where these nutrient predictions are available include hay, hay crop silage, corn silage, small grain silage, sorghum, straw, corn grain, and TMR.
Total fatty acids: Traditionally, the industry has evaluated fat by ether extract methods. This approach is flawed in that not only are fatty acids recovered, but so are compounds such as waxes, pigments, VFA and other ether soluble compounds. A more correct and nutritionally relevant approach is to determine actual fatty acids, generally by gas chromatography (GC) methods. The drawback with this is that it is costly and lab turn-around can be slow. CVAS has run hundreds of fatty acid evaluations by GC and generated NIR calibrations to allow this to be a practical evaluation.
Indigestible fiber: Another assay that is not routinely practical is the determination of indigestible fiber in forages. This is traditionally done by evaluating NDF after invitro incubations at longer time points. CVAS has determined 120 hours as an acceptable length of incubation for this determination. After running thousands of assays, we have put together NIR predictions for various forage types. Instead of estimating indigestible fiber using a standard thumb-rule of "lignin x 2.4," actual values can now be determined. These determinations allow for better qualitative evaluation of forage function in a diet, as well as improved predictions for rate of fiber digestibility.
Soluble fiber: This important nutrient fraction is comprised of primarily pectin and other fast-digesting cell wall compounds. It is a difficult fraction to determine, and has recently been available on a limited basis, calculated by difference after performing multiple assays on a feed. CVAS has generated NIR calibrations for soluble fiber that are more accurate than the by difference approach. The nutritionist is now able to characterize the soluble fiber fraction routinely through this NIR evaluation.
These new nutrient evaluations are available as part of the NIR "Plus" Option at CVAS. An abbreviated table of values by feed type is shown below. More extensive summaries can be found at the CVAS Web site.