The N-acetyl neuraminic-acid content of the milk of various species

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Abstract
Average N-acetyl neuraminic-acid (NANA) content of milk from cow, sheep, goat, mare, donkey and sow (about 10 samples from each species) was 17·7, 10·1, 6·4, 6·1, 12·0 and 64·0mg/100 ml, of which 14·2, 8·4, 3·2, 3·1, 5·0 and 53·7mg/100 ml respectively was in the casein fraction. The NANA content of casein showed marked species variation ranging from an average of 2·18 % for the sow to 0·09 % for the goat.About 28 % of the casein NANA of mare's milk was liberated in the fraction soluble in 12 % TCA by the action of rennin at pH 6·6 compared with 75 and around 100 % for donkey's and sow's milk respectively; about half the total NANA in the casein of cow's, sheep's and goat's milk was released under the same conditions.