AAB Archives Animal Breeding AAB Arch. Anim. Breed. 2363-9822 FBN Dummerstorf Göttingen, Germany 10.5194/aab-43-621-2000 Verwertung der im Intestinum wachsender Bullen absorbierten essentiellen Aminosäuren Kluth H. 1 Gabel M. 2 Voigt J. 3 Schönhusen U. 3 Martin-Luther-Universität Halle/Wittenberg, Landwirtschaftliche Fakultät, Institut für Ernährungswissenschaften, Emil-Abderhaldenstraße 26, 06108 Halle/Saale, Germany Universität Rostock, Agrar- und Umweltwissenschliche Fakultät Institut für umweltgerechte Tierhaltung, Jusrus-von-Liebig-Weg 8, 18059 Rostock, Germany Forschungsinstitut für die Biologie landwirtschaftlicher Nutztiere, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany 10 10 2000 43 6 621 632 Copyright: © 2000 H. Kluth et al. 2000 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://aab.copernicus.org/articles/43/621/2000/aab-43-621-2000.html The full text article is available as a PDF file from https://aab.copernicus.org/articles/43/621/2000/aab-43-621-2000.pdf

Title ofthe paper: <b>The efficiency of utilization of intestinal digestible indispensable amino aeids in growing bulls</b><br> There are problems to determine the efficiency of protein deposition of intestinal absorbed amino aeids, because it cannot be exeluded that the amount of single or some indispensable amino acid (IAA) can influence the growing Performance of the animal. The dependence of amino acid gain on the flux of essential absorbable amino aeids into the duodenum was studied in growing bulls to calculate the utilization rate of these amino aeids. Four growing bulls (Schwarzbuntes Milchrind, BW: 240&ndash;310 kg) with duodenal T-type cannulas were fed diets varying in crude protein content. Energy level was 11,2 MJ ME/kg DM. The efficiency for the different absorbable IAA was decreased with increasing nutritional level. This is in contrast with the constant utilization factor ofthe protein evaluation system (AfB, 1995; 1997). The efficiency of utilization of apparently digestible IAA for protein retention was highest for His and Met and amounted to 33 (He), 34 (Phe and Thr), 38 (Lys and Val), 41 (Leu), 52 (Met) und 76 (His) %, respectively. The intersection ofthe regression curve (AA-deposition against apparently digestible AA) with the abscissae resulted in the maintenance requirement of absorbable amino acid. For growing bulls (BW: 300 kg) a value of 4,7 g/d histidine and 4,2 g/d methionine was determined, but more investigations are necessary in this field.