Nature of the Blood Folates in Young Chicks and Poults Fed Pteroylmonoglutamic Acid or Pteroylheptaglutamates

(1) Chick and poult blood folates were measured microbiologically, using L. casei, S. jaecalis and P. cerevisiae, with and without incubation with chicken pancreas conjugase. Before incubation with conjugase, folate activity was low in blood of both chicks and poults. It increased greatly, particularly for L. casei, following incubation with chicken pancreas. (2) The use of pteroylmonoglutamic acid or pteroylheptagluta-mates (in brewer's dried yeast) as different sources of dietary folic acid did not alter the form of folate activities found by L. casei, S. jaecalis, or P. cerevisiae in chick or poult blood, either before or after incubation with chicken pancreas. (3) The major folate activity in both chick and poult blood was present as a form which was most active for L. casei following chicken pancreas conjugase treatment. Therefore, folate appears to be present in chick and poult blood mainly as a conjugate of N5-methyl-tetra-hydropteroyl-glutamic acid. (4) Although the extent of dilution of portal blood with systemic blood was not measured, the very low level of pteroylmonoglutamic acid in portal blood coupled with the approximately equivalent levels of conjugated folate active for L. casei in both portal and systemic blood indicate that both pteroylmonoglutamic acid and the pteroyl polyglutamates of brewer's yeast may be transformed to a conjugate of N5-methyl-tetra-hydropteroylglutamic acid in the intestinal mucosa.