Characterization of folate-dependent enzymes and indices of folate status in laying hens supplemented with folic acid or 5-methyltetrahydrofolate

Poult Sci. 2010 Apr;89(4):688-96. doi: 10.3382/ps.2009-00417.

Abstract

The conversion of folic acid (FA) to the biologically active 5-methyltetrahydrofolate (5-MTHF) is necessary for the deposition of folate in the egg. A study was conducted to compare egg folate concentrations, indices of folate status, and activities of folate-dependent enzymes in response to equimolar intake of either FA or 5-MTHF in laying hens. Forty-eight laying hens, 24 wk of age, from 2 different strains (Shaver White and Shaver Brown) were randomly assigned to receive 1 of 3 (n = 8 per strain) dietary treatments: 1) basal diet with no supplemental folate, 2) basal diet + 10 mg/kg of FA, or 3) basal diet + 11.3 mg/kg of 5-MTHF for 3 wk. A completely randomized design with 3 dietary treatments and 2 laying hen strains in a 3 x 2 factorial arrangement was used. Data were subjected to ANOVA, using the PROC GLM procedure of SAS. Plasma homocysteine, serum, and egg folate concentrations; hepatic serine hydroxymethyltransferase; and methionine synthase activity were affected by dietary folate supplementation but not by its form (FA and 5-MTHF). Relative to control hens, plasma homocysteine was decreased (P < 0.05) by 14.2%, whereas serum and egg folate were increased (P < 0.05) by 78.3 and 61.8%, respectively, in hens consuming either folate compound. Hepatic serine hydroxymethyltransferase and methionine synthase activity were increased and decreased (P < 0.05), respectively, in folate-fed birds compared with control-fed birds. Hepatic dihydrofolate reductase was influenced by both the addition and form of dietary folate, being higher (P < 0.05) in FA-fed birds than in 5-MTHF and control-fed birds. Feed efficiency was improved (P < 0.05) in 5-MTHF-fed birds relative to FA-fed birds. Strain of hen influenced serum folate and plasma homocysteine concentrations but not other indices of folate metabolism. Overall, FA and 5-MTHF have equivalent effects in enhancing egg folate concentrations and improving folate status in laying hens. Also, supplementation and form of folate may modulate the activity of folate-dependent enzymes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Feed
  • Animals
  • Chickens
  • Dietary Supplements
  • Duodenum / enzymology
  • Energy Intake
  • Female
  • Folic Acid / metabolism*
  • Folic Acid / pharmacology*
  • Glycine Hydroxymethyltransferase / metabolism*
  • Liver / enzymology
  • Methylenetetrahydrofolate Reductase (NADPH2) / metabolism*
  • Oviposition
  • Tetrahydrofolate Dehydrogenase / metabolism*
  • Tetrahydrofolates / metabolism*
  • Tetrahydrofolates / pharmacology*
  • Triticum

Substances

  • Tetrahydrofolates
  • Folic Acid
  • Methylenetetrahydrofolate Reductase (NADPH2)
  • Tetrahydrofolate Dehydrogenase
  • Glycine Hydroxymethyltransferase
  • 5-methyltetrahydrofolate