Prediction of chemical, nutritive and agronomic characteristics of wheat by near infrared spectroscopy

Near infrared spectroscopy (NIRS) is widely used in the flour milling indus try for rapid determination of moisture and protein in wheat. However, thes e measurements give little indication of the nutritive value of wheat when fed to poultry or pigs. Accurate estimates of nutritive value require speci alist facilities and are time-consuming and costly. Accordingly, prediction from chemical or NIRS measurements would be of some considerable benefit. In the current study 160 samples of wheat, representing 24 different variet ies, were used to generate NIRS calibration equations for chemical, nutriti ve and agronomic characteristics. Predictions of chemical constituents in w heat were very accurate. Coefficients of determination (r(2)) were 0.94 for dry matter, 0.90 for crude protein, 0.97 for ash, 0.78 for starch and 0.98 for oil. True metabolizable energy in broiler chickens was predicted more accurately (r(2) = 0.52 for adult birds, 0.74 for young birds) than apparen t metabolizable energy (r(2) = 0.45). Digestible energy (r(2) = 0.17) and n itrogen digestibility (r(2) = 0.22) in pigs were not predicted very accurat ely on a smaller subset (n=33). Agronomic characteristics were predicted ve ry accurately (r(2) = 0.98 hardness, 0.80 bushel weight, 0.99 thousand-grai n weight). Predictions of nutritive value of wheat from chemical or agronom ic characteristics are very inaccurate, since coefficients of determination vary from zero to 0.25. It is concluded that NIRS can accurately estimate the chemical composition of wheat, but accurate prediction of nutritive val ue is reduced by animal variation. Nevertheless, NIRS is potentially more r eliable for assessing nutritive value than chemical composition or agronomi c characteristics.