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Iron overload disorder has been described in a number of zoo-managed species, and it has been recommended to increase the tannin composition of the diet as a safeway to minimize iron absorption in these iron-sensitive species. The goal of this studywas to examine the potential of near infrared reflectance spectroscopy (NIRS) as a rapid and simple screening tool to assess willow (Salix caroliniana) nutrient composition (crude protein: CP; acid detergent fiber: ADF; neutral detergent fiber: NDF; lignin, gross energy: GE) and condensed tannin (CT) concentrations. Calibration equations were developed by regression of the lab values from2 years using partial least squares on n=144 NIRS spectra to predict n=20 independent validation samples. Using the full 2-year dataset, good prediction statistics were obtained for CP,ADF,NDF, and GEin plant leaves and stems (r²>0.75). NIRSdid not predict lignin concentrations reliably (leaves r²=0.52, stems r²=0.33); however, CTs were predictedmoderately well (leaves r²=0.72, stems r²=0.67). These data indicate that NIRS can be used to quantify several key nutrients in willow leaves and stems including concentrations of plant secondary compounds which, depending on the bioactivity of the compound, may be targeted to feed iron-sensitive browsing animals. [ABSTRACT FROM AUTHOR]