title: [15N-labeling of fishes using 15N isotopes in aquarium water and the effect of a different protein nutrient on the 15N elimination after the labeling period].
abstract: In a preexperiment of 12 days fishes (Cyprinus carpio L.) were labelled with 15N by means of 15NH4Cl and 15N-urea resp. in the aquarium water and by feeding a protein free diet. 15NH4Cl yielded a higher atom-% 15N excess (15N') in the tissues of fishes. In the main experiment 75 fishes (Cyprinus carpio L.) were 15N-labelled with 100 mg 15N'/l water from 15NH4Cl (95 atom-% 15N') in a protein free preperiod of 12 days. In the following main period the fishes received different protein sources in their diets in maintenance. A group of 20 fishes received an animal protein (fish meal) and two groups of 20 fishes each received plant proteins (soybean meal and wheat gluten resp.). The atom-% 15N' reached after the 15N-labelling period following values: digestive tract with content--7.15, liver--5.65, gills--5.89, muscle--0.81 and chorda dorsalis--1.09 respectively. During the main period (with protein feeding) the atom-% 15N' decreased in the tissues with high protein turnover (liver and gills) on the 2nd and 4th day to 4.31 +/- 0.11 (animal protein) and 4.64 +/- 0.14 (plant proteins) in average. The corresponding values in the tissues with low protein turnover (muscle and chorda dorsalis) were 0.73 +/- 0.04 and 0.80 +/- 0.04 atom-% 15N' in average. From the measurements on the 6th, 8th and 10th day of protein feeding resulted an atom-% 15N' in average of liver and gills of 4.08 +/- 0.13 (animal protein) and 4.11 +/- 0.15 (plant proteins). In muscle and chorda dorsalis the atom-% 15N' ascended in this time upon 0.80 +/- 0.04 (animal protein) and 0.90 +/- 0.03 (plant proteins). It seems that the protein metabolism of fishes is favoured from the amino acid of plant protein in comparison to animal protein to reduce the 15N-loss of the 15N-labelled body in maintenance, like the results from experiments with rats (Hernandez et al., 1981).
mesh_terms: D000821:Animal Feed; D000818:Animals; D002347:Carps / Q000378:metabolism*; D004044:Dietary Proteins / Q000493:pharmacokinetics*; D004435:Eating; D005396:Fish Products; D005398:Fisheries; D007553:Isotope Labeling; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010940:Plant Proteins / Q000493:pharmacokinetics; D013025:Glycine max; D014908:Triticum
chemical_list: D004044:Dietary Proteins; D009587:Nitrogen Isotopes; D010940:Plant Proteins; D009584:Nitrogen
vernacular_title: 15N-Markierung von Fischen über 15N-isotope im Aquarienwasser und der Einfluss einer unterschiedlichen Eiweissernährung auf die 15N-Eliminierung nach der Markierungsperiode.