USING NEAR -INFRARED REFLECTANCE SPECTROSCOPY (NIRS) TO PREDICT THE DIGESTIBLE PROTEIN AND ENERGY VALUE OF LUPIN KERNEL MEALS WHEN FED TO RAINBOW TROUT ,

As with all raw materials, learning to manage variability is one of the major limitations to improved adoption and maximisation of the value of lupins. Over a five-year period, 10 separate digestibility experiments were undertaken to examine the digestibility of protein and energy from 136 different samples of lupin meal. The digestibility of protein and energy to rainbow trout (Oncorhynchys mykiss ) was assessed for each of the meals. Digestible protein values ranged from 304 to 547 g/kg DM and digestible energy values ranged from 9.9 to 14.5 MJ/kg DM. The digestible protein and energy values were then assessed using multiple regression techniques to determine which compositional parameters accounted for the majority of the variability. This study demonstrated that within one raw material type not only does significant variability in the digestible value of lupin meals exist, but that it is possible to identify compositional features of that raw material that are intrinsically influencing their digestible value. Further assessment of these samples using nearinfrared spectroscopy (NIRS) shows that there are certain wavelengths that correlate with compositional attributes of the lupin meals relevant to their digestible value. From this work it has been possible to develop a calibration to predict both digestible protein and energy content of lupin kernel meals.