The nutritive value of mixed proteins. The biological value of the proteins of a mixture of yellow maize seed and grape seeds, and a mixture of yellow maize seed and camelthorn pods (Acacia giraffae)

Abstract

1. Feeding camelthorn pods (13 per cent. crude protein) with maize to rats does not improve the nutritive value of the maize proteins. When the camelthorn pods are mixed with maize seed in the proportion 1 to 3, the biological value is slightly higher than that of the maize alone, but due to a lower true digestibility, the nett percentage utilization of the nitrogen in the mixture was decidedly lower. 2. Again, a mixture of grape seeds and maize seeds in the proportion of 1 to 3, yielded a higher biological value than the maize alone, but here also a lower true digestibility of the mixture resulted in a lower nett utilization of the nitrogen. 3. In these cases the biological value as an index of the nutritive value of the proteins, without considering the digestibilities, gives a somewhat misleading result. The nett utilization, calculated from both the biological value and the true digestibility yield a more accurate result and gives a better reflection of the nutritive value of the proteins. 4. The mixture of grape seeds and maize seeds proved to be superior to the mixture of camelthorn pods and maize seeds.