Use of Tuna Liver Meal as Partial Replacement of Fishmeal in Diets for Nile Tilapia Fry, Oreochromis niloticus

A 13-week feeding experiment was conducted to evaluate the use of tuna liver meal as a replacement for fishmeal in diets for Nile tilapia fry, Oreochromis niloticus. Six isonitrogenous (40%) and isoenergetic (18 kJ digestible energy/g) diets were formulated in which tuna liver meal replaced 0 (control), 10%, 20%, 30%, 40%, or 50% of the protein supplied by fishmeal. Triplicate groups of fish (2.29±0.07 g) were fed twice daily to apparent satiation. Results showed that final weight, weight gain, and specific growth rate of fish fed diets in which up to 30% of the protein was replaced by tuna liver meal did not significantly differ from fish fed the control diet. There were no significant differences in feed intake or protein efficiency ratio of fish fed diets containing up to 30% replacement. The apparent digestibility coefficients (ADC) of protein and energy significantly dropped with the increase in dietary tuna liver meal but there were no significant differences in the ADC of dry matter or lipid. There were no significant differences in protein or ash contents in the fish body, but dry matter and lipid contents significantly differed among treatments. Results indicate that up to 30% of fishmeal protein can be replaced by tuna liver meal in Nile tilapia fry diets without adverse effects on growth performance or feed efficiency.