Why do we need a new NRC data base?

The National Research Council (NRC) feedstuff composition tables have been widely used by nutritionists, feed manufacturers and livestock producers. In spite of changes in crop varieties, soil fertilization practices and processing methods, there has been no systematic up-dating of the tables in recent years. A recent survey comparing the mineral concentrations of common feedstuffs as determined by commercial laboratories with NRC values showed marked discrepancies. For example, the sodium, copper, zinc and manganese concentrations determined by commercial laboratories were much lower than NRC values for several common feedstuffs. In addition, the standard deviations were often nearly equal to the mean values. For the NRC tables to continue as the standard, a systematic up-dating is required where a mean value, standard deviation and the number of samples analyzed is reported for each nutrient.