Dietary folic acid requirement of fingerling Channa punctatus (Bloch) based on growth, protein productive value and liver folic acid concentrations

Abstract

The aim of the study was to carry out a feeding trial to evaluate the dietary folic acid requirement of fingerling Channa punctatus (4.88 ± 0.74 g) by measuring the changes in growth indices and liver folic acid concentrations fed purified diets (450 g/kg CP, 18.39 kJ/g GE) containing seven doses of folic acid (0, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 mg/kg diet) to triplicate groups until satiation for 12 weeks. A significant cubic response of percent weight gain per cent (PWG), feed conversion ratio (FCR), protein efficiency ratio (PER), protein production value (PPV) and RNA/DNA ratio was recorded and improved with the increasing doses of dietary folic acid up to 0.75 mg/kg, whereupon the response attained a plateau. Hemoglobin (Hb), hematocrit (Hct), red blood corpuscles (RBCs) counts, mean cell hemoglobin (MCH) and mean cell volume (MCV) improved as the dietary folic acid concentration increased from 0 to 0.75 mg/kg diet and then response reached an almost constant. Superoxidase dismutase and catalase activities also supported the pattern of growth and hematological indices whereas hepatic thiobarbituric acid reactive substances (TBARS) concentration showed reverse pattern. A direct significant cubic association of liver folic acid concentrations to the increasing doses of dietary folic acid up to 1.0 mg/kg was evident. The precise estimate of dietary folic acid requirement of fingerling C. punctatus was made by subjecting the PWG, PPV and liver folic acid concentrations against different doses of dietary folic acid to broken-line analysis which revealed the requirement in the range of 0.74–1.15 mg/kg.