Changes of Amino-Acid Levels in Hydrolyzates of Bacteria Adhered to the Ovine Ruminal Wall During Feeding with High and Low Nitrogen Diets

Veterinarni Medicina 37, 1992, 293-305

The effects of low and high nitrogen diets on amino acid levels were studied in hydrolyzates of ruminal bacteria adhered to four topographically different anatomic parts of the ruminal wall (dorsal, ventral and caudal parts as well as reticulum) in 18 sheeps of the Slovak Merino breed divided into three experimental groups the epimural bacteria of the dorsal and ventral parts of the ovine rumen revealed the most sensitive reaction to the varying amounts of nitrogen ingested with the diet. In hydrolyzates of ruminal bacteria adhered to the dorsal and ventral epithelium, 15 and 14 amino acids were changing (Figs. 1, 2). In hydrolyzates of epimural bacteria, a sensitive reaction was observed in the following amino acids: alanin, histidin, thyrosin, arginin and prolin (Tabs. I-IV). In all topographical and anatomical parts of the rumen, both alanin and histidin levels in hydrolyzates of epimural ruminal bacteria significantly increased with the diet with high-nitrogen content fed, but was falling in sheep fed with low-nitrogen diet. Changes in alanin concentrations may be explained by the fact that alanin forms a part of the mechanism for short-time storage of ammonia in bacterial cells (Bartos, 1987). The fact that alanin is in its lack deaminated to pyruvate (Havassy, 1976) is explained by significant fall in alanin contained in hydrolyzates of bacterial proteins when fed low nitrogen diets. Significant fall in alanin in shortage of amino acid boud nitrogen can be explained by the fact that under these conditions, the alanin skeleton is being incorporated in to 80 % of amino acids synthetized de novo by ruminal bacteria (Syvaoja and Kreula, 1980). When sheep flock was fed the high-nitrogen diet, thyrosin and prolin levels were significantly reduced in hydrolyzates of epimural bacteria from all parts of the rumen, while low-nitrogen diet significantly increased the concentrations of both given amino acids in comparison with the control. Bartos (1987) gives in his study the table containing weight representation of different amino acids in proteins of bacteria of the ruminal content compiled on the basis of data of several authors. These data principally correspond to the results of our measurements in hydrolyzates of epimural bacteria. The highest weight representation of amino acids in hydrolyzates of epimural bacteria was found for glutamic acid, aspartic acid and arginine, while the lowest ones were detected for thyrosin, prolin and phenylalanin. The sequence of amino acids according to weight representation in hydrolyzates of epimural bacteria investigated by us, and the sequence of amino acids according to weight representation in bacterial proteins as referred by Bartos (1987) is presented in Tab. V. Changes in amino acid composition of proteins observed in bacteria adhered to the ruminal epithelium do not support the suggestion of some authors according to which bacteria adhered to the ruminal epithelium reveal both low sensitivity to feeding changes and low dependence on the diet. Our experiments demonstrated that the ingestion of various nitrogen levels in the diet resulted in the changes in amino acids levels in bacteria adhered to epithelium of the dorsal, ventral and caudal parts of the rumen as well as reticulum

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