Estimates of Additive Genetic Effects, Maternal Genetic Effects, Individual Heterosis, Maternal Heterosis, and Egg Cytoplasmic Effects for Growth in Tilapia nilotica

Abstract Lengths and weights of Auburn University‐Egypt and Auburn University‐Ivory Coast strains of Tilapia nilotica and their F1 F2, and backcross hybrids were analyzed by multiple regression to estimate strain additive genetic effects, strain maternal genetic effects, individual heterosis (specific combining ability), maternal heterosis, and strain egg cytoplasmic effects for growth to determine why heterosis of the F2 and backcross hybrids was greater than that of the FI hybrids. Individual heterosis and maternal heterosis made the greatest contributions to growth. The F2 and backcross hybrids were larger than the F1 hybrids because of maternal heterosis. Regression coefficients were used to predict growth for any possible hybrid combination. Egypt ♀× Ivory Coast ♂ FI hybrid females backcrossed to Egypt males and Egypt ♀× Ivory Coast ♂ F2 hybrids were the largest groups evaluated in this study and were also predicted to have faster growth rates than any other possible Egypt‐Ivory Coast hybrid.