Biological assessment of protein quality. Essential amino acid requirements of young rats in certain states of nitrogen balance.

The nutritive value of dietary proteins depends on, inter alia the degree of correspondence between the essential amino acid (EAA) content of the protein and the EAA requirements of the animal in question. In the present study the EAA requirements of the young male rat for the maintenance of nitrogen balance equal to 0; + 100; + 200; or + 300 mg N/100 g body mass/8 days were estimated. It was found that, probably because of time-dependent adaptive changes, there are differences, mainly between the EAA pattern for maintenance of N balance = 100 mg and higher. This finding is discussed with reference to its bearing on the methodology of protein evaluation and on the assessment of EAA requirements in general.