Dynamics of the amino acid and protein metabolism of laying hens after the application of 15N-labelled wheat protein. 4

12 colostomized laying hybrids with an 81% laying performance received 36 g wheat containing a 15N excess (15N') of 14.37 atom-% in a customary ration over 4 days. The wheat lysine contained 13.58 atom-% 15N', histidine 14.38 and arginine 13.63 atom-% 15N'. In the 4-day period of 15N' application 540 mg 15N', 18.1 mg lysine 15N', 21.5 mg histidine 15N' and 47.9 mg arginine 15N' were consumed per hen. Subsequently the animals received the same ration with unlabelled wheat. 12 h, 36 h, 60 h and 108 h after the last 15N' application 3 animals each were butchered. The atom-% 15N' of the lysine was below that of the two other basic and of the non-basic amino acids. The labelling of the amino acids of the egg white decreased rapidly 2 days after 15N' application. The atom-% of the 15N' of the yolk of egg, however, increased after the discontinuation and remained the same for 4 days after the last 15N' application. The 14N and 15N' amounts measured in the complete experiment period are distributed over the 3 basic and the 12 non-basic (excluding thioamino acids) amino acids in the white of egg for 14N as 25.0%:57.6% and for 15N' as 18.2%:57.5%. In the yolk of egg 28.5% 14N for the basic and 56.8% for the non-basic amino acids could be calculated; the corresponding values for 15N' were 17.8% and 55.5%. (author)