Genetic parameter analyses of growth traits at 30 days post-hatching in bighead carp (Hypophthalmichthy nobilis)

The aim of this study was to estimate the genetic improvement potential of early growth traits in bighead carp (Hypophthalmichthy nobilis). The practices of mass spawning (group 1) and artificial insemination (group 2) were carried out using two populations of H. nobilis, and 672 fries at 30 dph (days post-hatching) were collected from each group, that were used for the further analyses of early growth traits. Based on microsatellite markers, total of 628 and 660 individuals from group 1 and group 2, respectively, were assigned with unambiguous pedigrees and reconstructed with population diallel cross combinations. Extremely significant unequal parental contributions were detected in both groups. The extremely significant differences in BW (body weight) and SL (standard length) were detected among families in both groups, and the significant differences in BW and SL were detected among diallel cross combinations in group 2. Furthermore, the positive values in mid-parent heterosis (0.39%–7.64%) and special combining ability (SCA) (0.01–0.02) of two growth traits were detected in the hybridized combinations. Based on the animal model and restricted maximum likelihood (REML) algorithm, the heritability estimates of BW and SL in H. nobilis (30 dph) were calculated at 0.47 and 0.49, respectively. The extremely significant genetic and phenotypic correlations were found between BW and SL, with 0.89 and 0.83, respectively. The results indicated that the early growth traits of H. nobilis could be improved through family construction, cross breeding and selective breeding, but the unequal parental contribution should be taken into account in practical breeding programs.