A comparative study of muscle nutrition and intermuscular bone number in improved diploid carp

The common carp (Cyprinus carpio L., COC, 2n = 100) is one of the most widely consumed and distributed freshwater fish in the world. It ranks fourth in total freshwater aquaculture volume in various regions of China, behind Ctenopharyngodon idella, Hypophthalmichthys molitrix, and Aristichthys nobilis. However, in recent years, environmental degradation, inbreeding, disordered breeding, and other adverse effects have caused problems such as low seed quality and poor disease and stress resistance of the carp. In our laboratory, we developed two types of improved diploid carp the hybrid F1 of common carp (♀) × blunt snout bream (Megalobrama amblycephala, BSB, 2n = 48) (♂). To investigate the differences between IDC and IDMC compared to COC, in this study we compared the relevant characteristics of these two types of improved carp with those of COC in terms of muscle nutrient composition, intermuscular bone type, and number. The results showed that among the muscle nutrients, IDC had a higher protein content (18.50%) and lower carbohydrate content (0.70%). In addition, the unsaturated fatty acid content of IDC (3.45%) and IDMC (1.25%) were significantly higher than that of COC (P < 0.05) (0.50%). For monounsaturated fatty acids such as oleic acid (OA, C18:1 n-9) and linoleic acid (PA, C16:1), the content of IDC and IDMC were also abundant. In terms of intermuscular bone morphology, the morphology and type of intermuscular bone in IDC and IDMC medullary arch ossicles were consistent with those of COC. However, the number of intermuscular bones was different, and the average number of intermuscular bones of IDMC decreased by 14.77% (P < 0.05) compared with COC. The advantages of IDC and IDMC are different, with IDC having a higher value of muscle nutrients and IDMC having a lower intermuscular bone content. The distant hybridization of common carp (♀) × blunt snout bream (♂) developed two improved diploid carp varieties with excellent traits, which added carp germplasm resources with high muscle nutrition and lower intermuscular bone, and provided theoretical support for their production application.