F&F Aquaculture No. 1639 Effects of dietary methionine and lysine levels on the performance of juvenile Nile tilapia

Conclusion

• Response of juvenile Nile tilapia to 3 levels of dietary Met (0.77 %, 0.95 % and 1.15 %) and 4 levels of dietary Lys (1.2 %, 1.6 %, 2.0 %, and 2.4 %) were evaluated in 3×4 factorial design over a 56-d feeding trial.
• Datashowed main effects of both Met and Lys as well as their interaction (Lys xMet) effects on the performance of tilapia. Looking at the interaction effects,it was evident that fish responded to Met levels, only when the Lys was deficient.
• At1.2 % Lys level, increasing the Met level from 0.77 % to 0.95 % significantly improved feed intake, survival, growth, biomass gain, FCR and protein retention. However at higher Lys level (2.0 % or 2.4 %), Met levels did not affect the growth performance and feed utilization. Met requirements of tilapia increase (0.95 %) when the dietary Lys level is very low, probably because of the functional role of Met in ameliorating metabolic stress and improving immune function.
• Overall,data suggest that production performance of juvenile tilapia is optimized when the dietary Lys is 2.0 % diet and Met level is at least 0.77 % diet (as-fed basis).