ɛ-N-Methyl Lysine Metabolism in Sheep

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Abstract
Four experiments were conducted to gather initial information on ɛ-N-methyl lysine (NML) metabolism in sheep. In the first experiment, it was found that rumen microorganism did not contain NML. The effect of time after feeding on plasma lysine, histidine and NML levels was investigated in the second experiment. Results showed that after feeding, lysine declined and returned gradually to prefeeding levels; whereas, histidine and NML levels declined and then stayed below prefeeding levels the rest of the 20-hr, sampling period. In experiment 3, four alfalfa silages of varying dry matter (DM) but identical maturity were fed to sheep. The silage treatment which gave the highest DM intake and greatest N retention in sheep also resulted in the highest plasma methionine and NML levels. This concurrent elevation of methionine and NML levels may have metabolic significance since S-adenosyl methionine is the methylating agent of lysine during the synthesis of NML. In the last experiment four different protein sources were infused directly into the duodenum to vary the supply of methionine and lysine. It was found that when sheep were infused with soy protein and corn gluten, plasma methionine and NML levels were lower than when whole egg or casein was infused. A correlation coefficient (r=.92, approaching significance at P<.05) was calculated between mean plasma methionine and NML levels. These results suggested that methionine availability in some fashion affects regulation of NML synthesis and turnover. Copyright © 1971. American Society of Animal Science. Copyright 1971 by American Society of Animal Science.

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