Near-infrared reflectance spectroscopy (NIRS) appears to be superior to nitrogen-based regression as a rapid tool in predicting the poultry digestible amino acid content of commonly used feedstuffs

The ability of NIRS to predict the true ileal digestible amino acid content of commonly used feedstuffs was evaluated. Feed samples (n=263) tested for ileal digestibility in caecectomized cocks were scanned, and calibrations were developed using the feedstuff (category) of interest, as well as other feedstuff samples which improved the quality of the calibration ('expansion' samples). The resulting calibrations were able to explain 88-95% of the variation in digestible lysine, and 80-86% of the variation in digestible methionine in meat and bone meal, fishmeal, and poultry byproducts. For soybean meal and wheat grain, calibrations were obtained which explained 55-62% of the variation in digestible lysine and 64-84% of the variation in digestible methionine, the lower explained variation in lysine in these products being linked to the smaller number of samples available to make the calibration and the relatively smaller variation encountered in digestible lysine. Comparing the variation explained by NIRS with the variation explained by nitrogen-based regression showed that nitrogen-based regression worked equally well for wheat samples; however, for soybean meal and the animal meals NIRS was more accurate: the improvements in explained variation observed ranged from 14-81% points. These data thus suggest that NIRS is a tool which can be developed for the rapid prediction of the nutritional value of feedstuffs with a precision which makes it attractive for use as a routine quality control tool in feed mills. (C) 1998 Elsevier Science B.V.