Table 1. The distribution of endogenous nitrogen compounds of rumen ciliates The value inside () is % of each nitrogen on total non-protein nitrogen * Rumen ciliates were broken by Sonic Oscillation Apparatus (10KC) Table 4. The distribution of non-protein nitrogen compounds liberated in the medium (B-9) by autolysis of broken rumen ciliates Resume Amino acids and protein metabolism of rumen ciliate protozoa VI. Endogenous nitrogen compounds of rumen ciliates Endogenous nitrogen compounds of

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... en ciliate protozoa were examined. About 40% of non-protein nitrogen (NPN) endogenously liberated into the medium was ammonia-N and also about 40% was present as free amino acids. Small amount of peptide-N was also detected. It was confirmed that these nitrogen compounds were liberated in the culture medium not as a result of break and/or autolysis of dead ciliates but as a result of endogenous nitrogen metabolism of ciliates. Among amino acids of the endogenous NPN, alanine was most abundant and followed with proline, glutamic acid, lysine and valine. And the pattern of amino acids was almost equal even when carbohydrates were added into medium. Comparing the pattern of endogenous amino acids liberated into the medium with that of free amino acids in protozoan body, the most remarkable difference was the high value with the latter for aspartic acid. Therefore, it was thought that rumen ciliates have a selectivity in ingestion and/or excretion of amino acids, but as a whole, the amount of amino acids ingested was less than that of the excreted because of accumulation of amino acids in the medium. Ninhydrin blue unknown spot (US-1) of the endogenous amino acids of rumen ciliates was detected by paper chromatography, and the US-1 had already been identified as L-(-)-pipecolic acid.