The effects of folate sufficiency and deficiency in three pathways of folate metabolism were studied in 2- and 3-week-old broiler chicks. Erythrocyte phosphoribosylpyrophosphate concentrations and dihydro- folate reductase (EC 1.5.1.3) activity were significantly elevated in folate deficiency. Percentage incorporation of deoxyuridine into bone marrow DNA was reduced in folate deficiency. There was a trend towards reduced liver dihydrofolate reductase activity in deficient chicks. These studies identify further biochemical criteria that can be used to assess folate status of chicks.
