[Endogenous nitrogen metabolism processes in 15N-labeled swine. 2. Fecal excretion of amino acids and 15N-labeled amino acids with diets differing in crude fiber content].

Four pigs were labelled with 15N-ammonium salt over a period of 10 days in the feeding of a fishmeal diet, a fishmeal diet + partly hydrolysed straw meal, a field bean diet and a field bean diet + partly hydrolysed straw meal. The 14N-amino acids and the 15N-amino acids excreted in faeces showed highly significant correlation coefficients with the increasing content of crude fibre in the diets, which amounted to 3.0, 5.3, 10.0 and 12.1% in the DM. The following sequence was established for the growth angle (tan alpha) of the essential 14N-amino acids: Leu, Lys, Arg, Thr, Phe, Ile, Val, His and of the 15N-amino acids: Lys, Arg, Val, Leu, Ile, Thr, Phe and His. As Lys, His and Thr cannot incorporate 15N in transamination reactions in the intermediate metabolism, their level of labelling was considerable in case of diet 4. Nevertheless, tan alpha is highest for 15N-Lys and lowest for 15N-His. This means that His in contrast to Lys, parallel to increased synthesis, is also increasingly decomposed in the large intestine. In contrast to this, proline was not labelled with 15N even with the highest content of crude fibre in the diet. Despite this, 14N-proline excretion, next to glutamic acid, increased most with the growing content of crude fibre in the diet. Due to the hydrophilic character of glutamic acid and the increased water influx in the large intestine and the increased content of crude fibre in the diet, a growing proline transport parallel to the increased influx of crude fibre and water must be assumed. If the growth angle tan alpha for the excretion of 14N-amino acids is ascertained regressively for a crude fibre content of diet of 10%, one can prove from the proportion of the amino acids and a comparison from literature for faecal bacteria and ileum digesta that the amino acid composition for this measuring point largely corresponds to that of bacteria protein.