N-BALANCE INVESTIGATIONS WITH YOUNG BROILER-CHICKENS CONCERNING THE UTILIZATION OF DL-THREONINE AND DL-TRYPTOPHANE

It was the purpose of these investigations, apart from a methodical test of the procedure for the ascertainment of the efficiency of optical isomers of synthetic amino acids in an N-balance test, to draw conclusions concerning the value of DL-threonine and DL-Tryptophane for young chickens. The ascertained efficiency of 67% for DL-threonine (D-form 34%) resp. 86% for DL-tryptophane (D-form 72%) coincides with the results described in literature and speaks in favour of the method applied on the basis of the parameters of the efficiency graph of the limiting amino acids. The supposition made here that for a zero content of limiting amino acids the b-value also equals zero, requires further investigation. The clarification of the reasons for the low effectivity of the synthetic L-form ascertained in comparison with the native amino acid also makes further investigation necessary.