Crossbreeding effects on carcass traits in crossing Red Tilapia and Nile Tilapia fishes

A three-year crossbreeding experiment was conducted between males of Red Tilapia fish (RT) and females of Nile Tilapia fish (NT) to obtain F1 crossbred (½RT½NT), followed by inter-se mating to produce F2 crossbred (½RT½NT)². A total number of 40 sires, 120 dams, and 1206 fish at slaughtering at 28 weeks of age were used to estimate heritabilities, breeding values (EBV), direct additive genetic effects (GI), maternal effects (GM), direct heterosis (HI), and maternal heterosis (HM) for carcass traits in terms of slaughter weight (SW), carcass weight (CW), trunk weight (TW), viscera weight (VW), head weight (HW), fillet weight (FW), and fillet yield (FY). Fishes of interse crossbred (½RT½NT)2 have shown the highest ranges in EBV for carcass traits, while the other three groups (RT, NT, and ½RT½NT) have shown inconsistent trends. The percentages of GI were in favor of NT fish relative to RT fish by 9.8, 11.5, 23.6, 5.6, 3.9, 23.5, and 13.7% for SW, CW, TW, VW, HW, FW, and FY traits, respectively (P ≤ 0.01), while the percentages of GM were in favor of RT fish by 3.9, 5.8, 5.1, 7.3, 7.2, 6.5, and 4.4% for the corresponding traits (P ≤ 0.01). The estimates of HI and HM were positive and significantly moderate or high, with HI superiority ranging from 19.9 to 43.7% and favorable HM percentages ranging from 4.1 to 16.2%.