Abstract
A feeding trial was conducted to estimate the dietary folic acid requirement of juvenile tilapia, Oreochromis niloticus×O. aureus. Purified basal diets with eight levels (0.0, 0.3, 0.6, 1.0, 3.0, 6.0, 10.0, 20.0 mg/kg diet) of supplemental folic acid were fed to tilapia (mean initial weight 0.41±0.01 g) for 8 weeks. Each diet was fed to three replicate groups of fish reared in a closed recirculating system. Results indicated that weight gain and feed efficiency (FE) were significantly (P<0.05) greater in fish fed ≥1.0 mg folic acid/kg diet than fish fed 0.3 mg folic acid/kg diet or the unsupplemented control diet. Mortality of fish was not affected by dietary treatment. Hepatic folic acid concentration increased with an increase in dietary folic acid and values were significantly higher in fish fed ≥6.0 mg folic acid/kg diet than fish fed the control diet. An analysis of the weight gain percentage by broken-line regression indicates that the adequate dietary folic acid requirement in juvenile tilapia is 0.82 mg/kg diet.
