Genetic parameter estimates for intermuscular bone in blunt snout bream (Megalobrama amblycephala) based on a microsatellite-based pedigree

Most of the freshwater aquaculture fish species in the world, especially cyprinid fishes, contain intermuscular bones (IBs). IBs are often small and sharp, and they consequently limit how the fish can be processed, cause injury or trauma if lodged in consumers' throat or mouth and therefore affect the appeal of the fish to many consumers. In order to assess the possibility of decreasing IBs counts through selective breeding, this study evaluated the heritability of the number of IBs in blunt snout bream (Megalobrama amblycephala), which is one major aquaculture species in China. A total of 758 offsprings from 69 parents were genotyped at nine polymorphic microsatellite loci, and then 672 offspring from 213 full-sib families (33 female and 25 male breeders) were used for genetic parameter estimates. IBs were carefully teased from different poached sections of the flesh and counted. Heritability was estimated using an animal model. The results showed that IB number ranged between 84 and 146 per individual in the test population, with an average of 118 IBs. Coefficient of variation in IB number (CV) in ventral sections (13.63%) was substantially higher in comparison to dorsal sections (6.60%). The genetic correlation of IB number between the two sections was significantly positive and high (0.93) (P < .01), however, the phenotypic correlation was significantly positive but low (0.26) (P < .01). The differences among the families showed that the variation in the ventral section accounted for most of the total variation in IB number within the species, which indicated that IBs may have develop by different processes in dorsal and ventral sections. The heritability of the IBs number in M. amblycephala was low (0.098) for the dorsal section, but medium (0.236–0.410) for other sections. This study provides the first reported estimates for the heritability of the number of IBs in fish species and the finding of significant additive genetic variation for IB number indicate that it should be feasible to decrease the number of IBs through selective breeding.