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ARS Home » Plains Area » El Reno, Oklahoma » Grazinglands Research Laboratory » Forage and Livestock Production Research » Research » Publications at this Location » Publication #139370


item Pedro, Anne
item Northup, Brian

Submitted to: Biomedical Materials Research
Publication Type: Abstract Only
Publication Acceptance Date: 10/7/2000
Publication Date: 11/15/2000
Citation: Pedro, A., Northup, B.K. 2000. The capacity of near infraared reflectance spectroscopy (NIRS) to predict forage quality parameters of two warm-season grasses. Biomedical Materials Research. PP. 266-267.

Interpretive Summary: ABSTRACT ONLY

Technical Abstract: Forage produced by the grasses of tallgrass prairie is important to many livestock producers in central Oklahoma. Quality of these forage grasses changes during the growing season as plants mature. Rapid, accurate estimates of forage quality could be used to improve pasture management, but traditional assay techniques require large amounts of equipment and manpower, and results cannot be gained quickly. This study tested whether forage quality characteristics, normally determined by laboratory techniques, could be accurately defined by near infrared reflectance spectroscopy (NIRS). Samples of the warm-season grasses big bluestem (Andropogon gerardii) and little bluestem (Schizachyrium scoparium) were collected during April through September 2000 (11 dates) from plots (n=16) on a tallgrass prairie site in central Oklahoma. Samples were ground to a 2 mm particle size, scanned by NIRS, and analyzed for nitrogen content, total cell wall, and in vitro organic matter disappearance (IVOMD). Relationships between measured peaks of reflected wavelengths from NIRS (750-2500 nm range), and amounts of the characteristics described by wet laboratory procedures, were defined by regression techniques. Equations defining relationships between N content, as determined by laboratory analyses and NIRS, for the two species were significant (R^2=0.99; P<0.01) and the equations had similar slopes and y-intercepts. Equations defining the relationships between laboratory and NIRS-determined IVOMD (R^2>0.93; P<0.01) and total cell wall (R^2>0.91; P<0.01) were also significant, but the slopes and y-intercepts for the two species differed. These responses indicated forage quality of the two species changed in different ways during the growing season. Also, the strong relationships between laboratory and NIRS-determined characteristics showed that NIRS could be used to build databases to provide quick (and accurate) estimates of forage quality. Such assays would be useful in determining the timing (and amount) of supplementation for cattle. Data from additional years and locations are required to fully test the ability of NIRS to estimate forage quality of these grasses.