The effects of folate deficiency and oestradiol administration on the plasma free amino acid concentrations of the immature hen.

1. Free amino acid concentrations were measured in the blood plasma of immature pullets receiving a folate-deficient diet and injected with folate and/or oestradiol, with appropriate controls. 2. Folate deficiency caused a decrease and oestradiol administration an increase in the plasma concentration of most of the amino acids studied. 3. Plasma glycine concentration increased in foliate deficiency and decreased with oestradiol treatment. 4. All the observed effects could not be readily explained in terms of the known metabolic role of folate in amino acid metabolism. 5. The results did not indicate that the role of folate in amino acid metabolism was significant in the inhibition of oestradiol-stimulated oviduct growth.