Using near-infrared reflectance spectroscopy to predict the digestible protein and digestible energy values of diets when fed to barramundi,Lates calcarifer

This study examined the potential of using near-infrared spectroscopy (NIRS) to predict nutrient digestibility parameters (digestible protein and digestible energy) of compound diets when fed to barramundi. A series of 60 diets were assessed for their protein and energy digestibilities in a series of five experiments over a 5-year period from 2009 to 2014. Considerable variance was observed in the digestibility parameters of diets across the experiments, providing a suitable range in diet digestible protein and digestible energy values from which to develop a NIRS calibration. Samples of the same diets were also scanned using a diode array near-infrared spectrophotometer (DA-NIRS). The spectra were obtained by the DA-NIRS and were chemometrically calibrated against the digestible value data using multivariate analysis software. The results in terms of standard error of cross-validation (SECV), residual prediction deviation (RPD) and correlation coefficient (R2) show good relationships (R2 > 0.8) between the predicted and observed parameters for both the digestible protein and digestible energy parameters assessed. This study therefore demonstrates that it is possible to use NIRS technology to provide rapid estimates of the digestible protein and digestible energy values of compound diets for barramundi in near real time.