This study evaluated the effects of increasing levels of methionine supplementation on the success of almost total replacement of fish meal with soybean meal (SBM) in diets for hybrid tilapia. In this study fish were fed for 70 days a fish meal‐based diet or SBM‐based diets supplemented with five graded levels of DL‐methionine. Fish growth rate, feed conversion ratio and protein gain and retention efficiency improved significantly with increasing levels of dietary DL‐Met supplementation. Regression analysis of the effects of supplementing SBM‐based diet with graded levels of DL‐methionine indicated that a dietary methionine + cysteine level of 15.7 and 12.5 g kg/diet (as fed) was required to reach 95% of maximum weight and protein gain.
The researchers concluded that supplementation of SBM‐based diet with graded levels of DL‐methionine proved an effective strategy in reducing fish meal content in practical diets for hybrid tilapia.