Dietary folic acid requirement for maximum growth of juvenile tilapia Oreochromis niloticus × O. aureus
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.
(Department of Food Science, National Taiwan Ocean
University, Keelung, Taiwan 202, Tel: 886-2-2462-2192 ext. 5106. Fax: 886-2-2462-1684. Email: syshiau@mail.ntou.edu.tw)