Effect of Dietary Folic Acid Deficiency on Serine-Glycine Interconversion and the Activity of Liver Serine Hydroxymethyl Transferase in the Chick

Abstract

Three experiments were conducted to study the serine-glycine interconversion in chicks fed a casein diet and to investigate the effect of folic acid deficiency on this interconversion. The effects of dietary folic acid deficiency and tetrahydrofolic acid, when added in vitro, on the activity of serine hydroxymethyl transferase in the livers of chicks fed glycine or l-serine supplemented diets were also studied. Glycine improved growth and feed efficiency of chicks when added to the casein diet with no additional serine. An equimolar quantity of l-serine supported growth similar to that produced by glycine. However, when the diet was deficient in folic acid, l-serine was unable to replace glycine need for improving chick growth. There was always an improvement in growth when glycine was added regardless of the adequacy of folic acid. The activity of serine hydroxymethyl transferase in chick liver was not affected by the addition of glycine or l-serine when the diet was adequate in folic acid. The enzyme activity was depressed, however, in the absence of folic acid. The activity was further depressed when glycine or serine was added to the diet deficient in folic acid. The in vitro addition of tetrahydrofolic acid did not improve the enzyme activity in livers of chicks fed folic acid adequate diets but improved the activity in livers of those fed the folic acid deficient diet.