Genetic parameter estimates for growth of grass carp, Ctenopharyngodon idella, at 10 and 18 months of age

摘要

The aim of this study was to estimate the growth trait parameters in grass carp, Ctenopharyngodon idella, which is one of the major freshwater aquaculture species in China. The heritability, genetic and phenotypic correlations were estimated for body weight, standard length, body height and body thickness measurements of 10 and 18 month old fish. Analyses were performed on a total of 41 and 104 full-sib families of grass carp including 937 and 2454 individuals at 10 (first spring) and 18 months (second winter) of age, respectively. The families were reconstructed using the molecular pedigree based on twelve microsatellite loci, and 97.6% of the offspring were unambiguously assigned to single parent pairs. Unbalanced contributions to progeny were found among families and parents (P 0.01). Variance components and genetic parameters were estimated using the restricted maximum-likelihood algorithm with animal models. For all growth traits across two stages of grass carp, the common environment/maternal effect in proportion to phenotypic variance was very low (0.00-0.06), and not significant (P > 0.05). The heritability estimates for growth traits ranged from 0.24 to 0.38, and were significantly different from zero (P 0.01). These results indicated that the breeding population had considerable additive genetic variation in growth traits, and the ongoing selective breeding program should produce considerable genetic improvement in the growth traits of the grass carp. High genetic and phenotypic correlations were found among growth traits (0.81-0.99, P 0.01). These data indicate that selection for improved standard length will have a favorable effect on body weight in grass carp which is the key economic parameter for production yield. High and positive genetic correlations between growth traits at 10 and 18 months of age were also detected in grass carp (0.87-0.95, P 0.01), which indicated that individuals with higher growth performance at 10 months also grew to be better at 18 months. The results showed that genetic differences in growth traits among grass carp progeny could be determined earlier by measuring indicator traits predictive of long-term genetically determined growth.