Cysteine desulfhydrase activity in chick liver

The level of cysteine desulfhydrase activity present in the liver of the newly hatched chick is high. A rapid decline in liver cysteine desulfhydrase activity of chicks fed a purified ration containing pyridoxine occurred during the first 7 days after hatching, but the level of activity remained relatively constant thereafter. A deficiency of pyridoxine in the ration resulted in a decline in cysteine desulfhydrase activity, between 7 and 14 days of age, to a level approximately one-half of that found in chicks receiving pyridoxine. High levels of cysteine desulfhydrase activity, comparable to those found in the livers of newly hatched chicks, were maintained or restored in chicks fed either an egg ration or simulated egg rations.