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Day-old New Hampshire chicks maintained on a complete synthetic-type diet supplemented with 0.2% DL-ethionine grew very poorly, had a lowered survival rate, and developed fatty livers. Sex of the chick did not appear to influence the response to ethionine under these conditions. The toxic effects of ethionine could be totally overcome with additional methionine. Supplementary choline had a variable effect, whereas cystine and elemental sulfur increased the adverse effects of ethionine. A very high level of vitamin B12 failed to decrease ethionine toxicity. Addition of methionine at levels of 2 to 4% of an adequate diet was increasingly depressive upon growth by 4 weeks of age. Ethionine did not alter the toxicity of these high levels of methionine.

Investigations on vit. B12 in experimental animals have been hindered by the difficulty experienced in producing a clear-cut deficiency of the vitamin. In studies with chicks, most workers have achieved this end through use of second generation depleted birds or use of thyroid-active substances( 1-3). Attempts to enhance the severity of the vit. BIZ deficiency by dietary means have been successful to varying degrees. Schaefer, Salmon, and Strength( 4) obtained marked growth stimulation of non-depleted chicks when vit. B12 was added to a diet low in methionine and choline, which contained 19% lard. The effect of varying the level of lard upon the vit. BIZ deficiency was not studied. Hill and Branion(5) obtained a greater growth response with vit. B12 when 5% corn oil and 110% sodium proteinate were both added to an all-vegetable diet than when either was added alone or when both were omitted from the basal diet. Depression of growth in the absence of vit. BIZ with 1 to 4% glycine, 4% leucine, or 6 to 8% zein has been reported (6,7). This effect was overcome with vit.

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