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Two hundred thirty eight samples, representing 19 vegetable feedstuffs, were analyzed for total- and phytate phosphorus (P). Phytase activity was determined on a limited number of feedstuffs with an activity of more than 100 units kg(-1). Near infrared reflection spectra (NIRS) were taken between 1100 and 2500 nm in steps of 4 nm. By means of principal component analysis the feedstuffs were grouped in so called starchy (n = 150) and protein-rich feedstuffs (n = 88). NIRS-calibrations were developed using partial least square regression and tested by cross-validation. Total-P varied from 0.22 to 1.25% and phytate-P from 0.05 to 1.02% for starchy feedstuffs and respectively from 0.46 to 1.37% and from 0.22 to 0.56% for protein-rich feedstuffs. Within these broad ranges, NIRS-values were highly correlated to determined total- and phytate-P with prediction errors of 0.08% and 0.08 respectively for starchy feedstuffs and 0.08% and 0.04 respectively for protein-rich feedstuffs. However, considering the mostly small deviation of mean or calculated values for the separate feedstuffs, NIRS only makes practical sense to predict total-P for wheat by-products and phytate-P for maize gluten feed. On the other hand, NIRS could be used for unknown or not tabulated products. Spectral signals from total and phytate-P are partly based on direct responses from organic complexes but also on secondary relationships through protein and fat. NIRS seems not sensitive enough to detect phytase.
Original languageEnglish
JournalNetherlands Journal of Agricultural Science
Issue number4
Pages (from-to)357-369
Number of pages13
Publication statusPublished - 1-Dec-1994

ID: 206200