Improved Traits of Proximate Compositions, Liver Antioxidant Capacity and Feeding Habits in Diploid Hybrids from Female Micropterus Salmoides × Male Lepomis Cyanellus

Distant hybridization has been widely used as an effective strategy for improving fish germplasm. The largemouth bass (Micropterus salmoides, LB) is a popular fish worldwide due to its excellent performance in aquaculture, edibility, and sport fishing. However, the carnivorous nature of LB increases the cost and difficulty of culture and poses a threat to wild fishery resources. At present, there is a lack of research on improving the germplasm of LB. In this study, hybrid offspring (LG) were produced by crossing female LB and male green sunfish (Lepomis cyanellus, GS). The biological characteristics of the LG, such as muscle proximate compositions, liver antioxidant enzyme activity, and pharyngeal tooth structure, were analyzed to evaluate their potential for aquaculture. The proximate compositions analysis revealed that LG has a higher crude protein content of 20.07% compared to LB (18.1%) and GS (18.7%) (P < 0.05), and a lower crude fat content of 0.57% than LB (1.17%) (P < 0.05). Furthermore, LG had a significantly higher essential amino acid content (7.20%) than LB (6.43%) (P < 0.05), but not significantly different from GS (6.82%) (P > 0.05). In terms of fatty acid content, LG had significantly lower levels of saturated fatty acids (0.083%) compared to LB (0.153%) and GS (0.169%) (P < 0.05). Additionally, the amount of arachidonic acid (C20:4n6, ARA) in LG (0.058%) was significantly higher than LB (0.019%) and GS (0.043%) (P < 0.05). Regarding antioxidant enzyme activities in the liver, LG exhibited significantly higher superoxide dismutase (SOD) activity than LB and GS (P < 0.05). Electron microscopic observation of the pharyngeal tooth showed that the tooth number of LG (160.67 ± 3.93) was significantly lower than that of LB (181.67 ± 4.97) (P < 0.05) and significantly higher than that of GS (108.00 ± 3.58) (P < 0.05), while the tooth diameter of LG (0.076 ± 0.023) was significantly higher than that of LB (0.057 ± 0.016) (P < 0.05) and significantly lower than that of GS (0.108 ± 0.044) (P < 0.05). In conclusion, this study found that LG exhibited improved traits in proximate composition and hepatic antioxidant enzyme activity. The pharyngeal tooth characteristics indicated that LG may have different food selection and processing capabilities. This is the first report on biological characteristics in offspring produced from a distant hybridization between LB and GS, providing new insights into the genetic improvement and germplasm innovation of LB.