Changes in the amino acid levels in hydrolysates of bacteria adhering to the rumen in sheep during feeding with high and low nitrogen diets]

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 sheep + 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: alanine, histidine, thyroxin, arginine and proline (Tabs. I-IV). In all topographical and anatomical parts of the rumen, both alanine and histidine 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 alanine concentrations may be explained by the fact that alanine forms a part of the mechanism for short-time storage of ammonia in bacterial cells (Bartos, 1987). The fact that alanine is in its lack deaminated to pyruvate (Havassy, 1976) is explained by significant fall in alanine contained in hydrolyzates of bacterial proteins when fed low nitrogen diets. Significant fall in alanine in shortage of amino acid bound nitrogen can be explained by the fact that under these conditions, the alanine skeleton is being incorporated in to 80% of amino acids synthetized de novo by ruminal bacteria (Syv?oja and Kreula, 1980). When sheep flock was fed the high-nitrogen diet, thyroxin and proline 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 thyroxin, proline and phenylalanine.(ABSTRACT TRUNCATED AT 400 WORDS)