The obvious heterosis and genetic characters of intergeneric cross and backcross juveniles between blunt snout bream ( Megalobrama amblycephala ) and topmouth culter ( Culter alburnus )

In this study, we used artificial insemination to generate hybrid groups of fish [MC-F-1(MA female xCA male) and MC-F-2(MC-F-1 female x male)] by intergeneric crosses of Megalobrama amblycephala (MA) and Culter alburnus (CA); sequential backcrosses [CAM-B-1 (CA female xMC-F-1 male) and MCC-B-1 (MC-F-1 female xCA male)] were also performed. All these hybrids showed high rates of fertilization, hatching and survival (p > 0.05). For genetic traits, compared with those of the M. amblycephala and C. alburnus parental lines (Table 1), the fertilization rate, hatching rate and 7-day survival rate of MC-F1(MA female xCA male), MC-F2(MC-F1 female x male), CAM-B1 (CA female xMC-F1 male) and MCC-B1 (MC-F1 female xCA male) by artificial insemination exhibited similar high rates (p > 0.05). The morphology of the four hybrids MC-F-1/F-2,F- CAM-B-1 and MCC-B-1 were intermediate between those of their parents. Compared with their parents of MA and CA, weight gain rate (WG), specific growth rate (SGR) and protein efficiency ratio (PER) of hybrids MC-F-1/F-2, CAM-B-1 and MCC-B-1 were significantly (p 0.05) increased and feed conversion ratio (FCR) was significantly (p 0.05) decreased after 3 months feeding. Moreover, protein content of muscle for MC-F-1/F-2, CAM-B-1 and MCC-B-1 was significantly (p < 0.05) higher and carbohydrate content of muscle was significantly (p < 0.05) lower than their parents. The females and males of the four hybrids had normal gonadal development. In this study, we successfully generated intergeneric and backcross hybridization lines with fertile potential among fish of the Cultrinae subfamily and these hybrids had obvious heterosis in terms of growth performance, feed utilization and muscle quality.