The Near Infrared Reflectance (NIR) Spectroscopy technique can be
used for fast evaluation of the nutritional content of feedstuffs. This
method requires a sufficiently large number of chemically verified
analytical values for instrument calibration. The population of samples
used for calibration has to be representative in terms of type and
composition of the type of feedstuffs to be tested.
The NIR method is based on the construction of a comprehensive
calibration data set produced from samples that are analysed and
their nutritive content evaluated by means of reference methods. NIR
calibrations have been constructed for the amino acid composition
of several different types of raw materials of both plant and animal
origin (for example soy, wheat and fish meal). In addition, the
concentration of ileal digestible amino acids in raw materials can also
be estimated by NIR. However, the analysis by NIR of mixed feeds
for the determination of the concentration of total and supplemental
amino acids has not been met with the same success so the amino
acid analysis by NIR is not possible in mixed feeds. Nevertheless the
technique is of great value for optimising the utilisation of raw material
according to their actual amino acid content rather than calculated
values. 