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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Publications at this Location » Publication #324172
Title: Predicting water-soluble carbohydrates and ethanol-soluble carbohydrates in cool-season grasses with near-infrared reflectance spectroscopy

Author
item PRINCE, KELLY - University Of Kentucky
item GOFF, BEN - University Of Kentucky
item LAWRENCE, LAURIE - University Of Kentucky
item Kagan, Isabelle
item SMITH, RAY - University Of Kentucky

Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/9/2015
Publication Date: 1/12/2016
Citation: Prince, K., Goff, B., Lawrence, L., Kagan, I., Smith, R. 2016. Predicting water-soluble carbohydrates and ethanol-soluble carbohydrates in cool-season grasses with near-infrared reflectance spectroscopy. American Forage and Grassland Council Conference Proceedings. Pg. 1.

Interpretive Summary: Grazing animals may require a high or low total nonstructural carbohydrate diet for optimal health and production. Understanding how carbohydrates fluctuate in Kentucky pastures and being able to quantify and monitor carbohydrates in a timely manner will greatly aid in managing grazing animals in this region. However, using laboratory chemistry to quantify nonstructural carbohydrates can be time consuming and costly. The objective of this study was to develop calibrated equations for faster and easier analysis of water-soluble carbohydrates (WSC) and ethanol-soluble carbohydrates (ESC) in cool-season grasses in Kentucky using near-infrared reflectance spectroscopy (NIRS), which gathers information about carbohydrate composition of samples based on spectra rather than on laboratory chemistry. Eight cool-season grass cultivars consisting of Kentucky bluegrass, tall fescue, orchardgrass and perennial ryegrass were sampled every 7 to 14 days during the growing season from the University of Kentucky Research Farm in Lexington, KY. Samples were immediately flash frozen after sampling, freeze dried, and ground and analyzed by a NIRS spectrophotometer. WSC and ESC were determined using colorimetric phenol-sulfuric acid assays and served as the basis for NIRS calibration. Based on the statistics of these calibrations, the equations provided robust and accurate estimates of WSC and ESC. This method will aid in simple and timely monitoring of carbohydrate levels in pastures in the future, and will allow for the more efficient management of grazing animals.

Technical Abstract: Grazing animals may require a high or low total nonstructural carbohydrate diet for optimal health and production. Understanding how nonstructural carbohydrates fluctuate in Kentucky pastures and being able to quantify and monitor nonstructural carbohydrates in a timely manner will greatly aid in managing grazing animals in this region. However, using laboratory chemistry to quantify nonstructural carbohydrates can be time consuming and costly. The objective of this study was to develop calibrated equations for faster and easier analysis of water-soluble carbohydrates (WSC) and ethanol-soluble carbohydrates (ESC) in cool-season grasses in Kentucky using near-infrared reflectance spectroscopy (NIRS). Eight cool-season grass cultivars consisting of Kentucky bluegrass, tall fescue, orchardgrass and perennial ryegrass were sampled every 7 to 14 days during the growing season from the University of Kentucky Research Farm in Lexington, KY. Samples were immediately flash frozen after sampling, freeze dried, and ground and scanned into FOSS 6500 NIRS autosampler with ISIscan software. WSC and ESC were determined using colorimetric assays and served as the basis for NIRS calibration. Based on the statistics of these calibrations, the equations provided robust and accurate estimates of WSC and ESC. This method will aid in simple and timely monitoring of nonstructural carbohydrate levels in pastures in the future, and will allow for the more efficient management of grazing animals.