Comparison of growth, physiological and biochemical, muscle quality, and relative gene expression levels of hybrid and purebred offspring of Cyprinus carpio var. Longke−11 mirror and Cyprinus carpio haematopterus

To cultivate a new disease-resistant scaly carp strain, the following experimental groups were established: Cypinus carpio var. Longke − 11 mirror ♀ × ♂ (KK), C. carpio var. Longke − 11 mirror ♀ × C. carpio haematopterus ♂ (KH), C. carpio haematopterus ♀ × ♂ (HH), C. carpio haematopterus ♀ × C. carpio var. Longke-11 mirror ♂ (HK). Comparative studies were conducted on growth performance, physiological and biochemical indicators, muscle nutritional quality, and relative gene expression levels across the four groups. All experimental fish (405.01 ± 41.05 g) were reared together in a single net cage (4.0 m × 6.0 m × 5.0 m) for 140 days, with all parameters measured at the end of the experiment. For growth performance, the KH group exhibited significantly higher weight gain rate (WGR), specific growth rate (SGR), andsurvival rate (SR) than the other groups ( P < 0.05). The KH group demonstrated higher heterosis rates for weight and height traits than the HK group. Regarding physiological and biochemical indicators, alkaline phosphatase (ALP), albumin (ALB), urea (UREA), as well as lipase (LPS) and trypsin (TPS) in the KH group were significantly higher than those in the HH group ( P < 0.05). Catalase (CAT), superoxide dismutase (SOD) activities and malondialdehyde (MDA) content in the KH group were significantly superior to those in the other groups ( P < 0.05). In muscle nutritional quality, the KH group showed significantly higher crude fat, total saturated fatty acids (∑SFA), total n-3 polyunsaturated fatty acids (∑N-3 PUFA), and total n-3 long-chain polyunsaturated fatty acids (∑N-3 LC-PUFA) than the other groups ( P < 0.05). Additionally, the KH group had significantly higher total essential amino acids (∑EAA), and total amino acids (∑TAA) than the KK group ( P < 0.05); Regarding gene expression, the KH group exhibited significantly higher GH mRNA levels than the KK and HH groups ( P < 0.05), and IGF − 1 mRNA levels was significantly higher than the other groups ( P < 0.05). IL − 21R , TOR , and 4EBP2 mRNA levels in the KH group was significantly higher than in the HH and HK groups ( P < 0.05). In summary, the KH group demonstrated the most advantageous characteristics among the four experimental groups.