Evaluation of selective breeding effect of Oreochromis mossambicus and O.hornorum at fourth generation

Selective breeding were performed on the base populations of Oreochromis mossambicus and O.hornorum respectively, and F₄ generations were produced and evaluated. Compared with control group, the daily growth rate of F₄ of O.mossambicus and O.hornorum was improved by 27.96% and 36.73% (P < 0.05), and the average selection response per generation was 6.99% and 9.18%, while variation coefficient of body weight was reduced by 24.83% and 36.33% over the control group, respectively. At the first sex maturity, the mean body weight of the selected group F₄ was increased more than two times of the control group respectively, and their hybridsO.mossambicus ♀ (XX) × O.hornorum ♂ (ZZ)had high and stable male rate. All these results showed that selection response of the two kinds of tilapia is remarkable, and the individual growth rate was turned to be consistent in the selected population. It also indicated that there are still some selection potentials in F₄ generations, and it is feasible to proceed with selective breeding for growth of the two kinds of tilapia.