[15N-labeled lysine in colostomized laying hens. 5. 15N incorporation into blood fractions and the gastrointestinal tract]

[Dynamics of amino acid and protein metabolism of laying hens after administration of 15N-labeled wheat protein. 5. Incorporation of 15N into the blood fraction and its amino acids]

12 colostomized laying hens which received 15N labelled wheat over 4 days were butchered 12 h, 36 h, 60 h and 108 h (3 animals each) after the last 15N application. The intake of 15N excess (15N') from the wheat amounted to 540 mg 15N' during the application period. The 15N' in the blood plasma decreased after the last 15N' application from 0.76 atom-% to 0.55 atom-% after 108 h, the labelling of the corpuscular components at the same measuring points increased from 0.28 to 0.50 atom-% 15N'. 96.6% of the plasma 15N' and 93.8% of that in the corpuscles is precipitable in trichloric acetic acid. The atom-% 15N' of histidine in the total blood remained unchanged in dependence on the butchering time. The 15N amount in lysine and arginine and that in the non-basic amino acids decreased inconsiderably in the period between 12 h and 108 h after the last 15N' wheat feeding.

[15N transamination in the administration of various tracer substances. 1. Whole body studies in rats]

4 groups of 3 growing Wistar rats each were orally given either 15N methionine, 15N lysine, 15N glycine or 15N ammonia sulphate over 10 days. By means of measuring 15N, the 15N accumulation in the amino acids (AA) of the body protein, statements were to be made on the transamination of the individual 15N substances and thus their suitability as tracer substances for studies of N metabolism. None of the tested 15N AA achieved a proportionate labelling of all AA of the body protein. The AA used as tracer in each case showed the highest 15N labelling of all AA in the body. Of the amino 15N detected in the animal body, ca. 19% were found in Met after a 15N Met application, ca. 88% in Lys after a 15N Lys application and ca. 50% in Gly after a 15N Gly application. After the application of 15N ammonia sulphate ca. 42% of the body amino 15N are apportioned to the essential and ca. 58% to the non-essential AA. Thus this substance produces a more proportional labelling of the essential and non-essential AA of the body protein than 15N Gly. The following quotas of the 15N amounts applied were found in the AA of the animal bodies: tracer substance lysine 52%, glycine 32%, ammonia sulphate 24%, methionine 21%. After summing up the amino acid 15N amounts in the animal body, eliminating in each case the tracer AA and taking into account the molecular weight of the AA, there was a good agreement of the intensity of the accumulation of 15N in the individual AA, irrespective of the applied tracer substance: arginine, glutamic acid, cysteine and aspartic acid highest, threonine, phenylalanine and lysine lowest accumulation.

[Evaluation of 15N marked urea in the laying hen. 4. Incorporation of 15N in blood, its fractions and follicles in various developmental stages]

In order to study the utilization of urea in poultry, 3 colostomized laying hybrids were orally supplied with a traditional ration supplemented with 1% 15N'-labelled urea with a 15N excess (15N') of 96.06 atom-% over a period of 6 days. After another 2 days on which the hens received the same ration with unlabelled urea, they were butchered. The atom-% 15N' of the blood on an average of the 3 hens was 0.64, of the plasma 1.40 and of the corpuscles 0.47. The TCA-soluble fraction of the blood had an average 15N' of 1.14 atom-%; the 15N amount is 9.7% of the total amount of 15N in the blood. The amount of 15N' in the urea in the blood was 6.8 atom-%. This shows that the absorbed urea is decomposed very slowly. The quota of 15N' in the basic amino acids from the total 15N' of the blood plasma is only 0.3% and that of the corpuscles 2.2%. The average 15N' of the mature follicles is 2.39 atom-% whereas the smallest and the remaining ovary contain 1.12 atom-%. The labelling level of lysine in mature egg cells was, in contrast to this, only 0.08 atom-% 15N' and in infantile follicles 0.04 atom-% 15N'. 1% of the 15N' quota is in the follicles and the remaining ovary. Of the basic amino acids, histidine is most strongly labelled. The as a whole lower incorporation of the 15N from urea into the basic amino acids shows that the nitrogen of this compound can be used for the synthesis of the essential amino acids to a low degree only.

[Studies of 15N-labeled lysine in colostomized laying hens. 6. 15N incorporation into basic amino acids of the liver, kidney, meat, bones and remaining body as well as 15N balance]

Three colostomised laying hybrids received 91.40 mg L-lysine-15N-excess (15N') each over a period of four days in a metabolism experiment with 15N-labelled lysine. After another four days, during which the hens received the same rations supplemented by commercial L-lysine, the animals were butchered and divided into individual fractions. After the hydrochloric hydrolysis of the organs and tissues the heavy nitrogen of lysine, histidine and arginine were separated, quantitatively evaluated, processed and measured with an emission spectrometer. Atom-% 15N' on an average amounted to 0.20 in the liver, 0.16 in the kidneys, 0.06 in the meat and 0.05 in the bones. Of the rediscovered 15N' applied, faeces contained 8.1%, urine 18.3%, the eggs 24.3%, the blood 4.9%, the meat 20.5%, the bones 5.2%, the gastro-intestinal tract with its contents 4.5%, the liver 3.5%, the kidneys 0.9%, the reproductive organs 3.7% and the rest 6.1%. The quota of rediscovery of the 15N' applied was 95.7%. 62% of the total 15N' was rediscovered in eggs, body and faeces as lysine 15N'. There was significantly more 15N' in the arginine in all fractions than in the histidine. The quota of the lysine-15N' of the total 15N' differed considerably in the fractions: less than 40% bones and blood; 48...56% gastro-intestinal tract, faeces, oviduct, kidneys; 62...63% remaining ovary, rest; 69...71% eggs, meat, liver. It could be proved that the alpha-amino group of lysine is to a large extent incorporated into other amino acids. Further proof that the amino acid metabolism proceeds in two phases was submitted, i.e. hight amounts of amino acids previously deposited in the body are used for egg synthesis.