COMPARISON OF SHORT AND LONG WAVELENGTH OF NEAR INFRARED SPECTROSCOPY FOR PREDICTING NITROGEN AND ALLANTOIN IN URINE

Abstract

Total 130 urine samples collected from dairy cattle were studied for knowing the
possibility and accuracy of the use of long and short wavelength of near infrared spectroscopy (NIRS) for nitrogen and allantoin content in urine. The samples were randomly separated for the calibration (n=94) and the validation samples (n=36)_ Shon and long wave length of NIRS was selected in the range of 700-1350 and 1350-2500 nm, respectively. Four wavelengths selected from short wavelength were found mainly related to the N-I-1, C-H or O-H structure in both for nitrogen at 1225, 970, 1060 and 806 nm and for allantoin at 990, 1030, 1170 and 815 nm,
respectively. Meanwhile, the selection in long wavelength was found mainly related to the N-H bound or protein for each component at 1430, 1530, 2242 and 1960 nm for nitrogen and 2180, 2242, 1978 and 1530 nm for allantoin, respectively. Coefficient correlation (and standard error) of prediction uith calibration equations using short wavelength were 0.85 (0.19), and 0.85 (47.7) for nitrogen and allantoin, respectively. Those values obtained from long wavelength were found
to be 0.91 (0.13) and 0.92 (42.3), respectively. Judgement of validation with RPD values (the ratio of standard deviation of reference data in prediction sample to the standard error of prediction by NIR) for nitrogen and allantoin predicted by short wavelength were found 2.06 and 2.42, respectively. These values were lower than 2.5 the limit value recommended available for application. However, the use of long wavelength of NIRS showed an possibility to predict nitrogen and allantoin in urine as shown by high RPD values to be 2.94 and 2.70, respectively.