Effects of Dietary Strontium Supplementation on Growth Performance, Strontium Enrichment, Muscle Nutrition, and Hepatic Lipid Metabolism in Juvenile Hybrid Sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂)

To explore a safe and effective approach for producing strontium-enriched fish, in this study, we modified the feed for juvenile hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂) and set three different levels of strontium chloride content in their diet (0 mg/kg (Sr0, control), 80 mg/kg (Sr80), and 160 mg/kg (Sr160)) for a period of 8 weeks, analyzing their growth performance, strontium enrichment, muscle nutrition, and hepatic physiological, biochemical, and transcriptomic characteristics. The results show that dietary strontium had no significant impact on sturgeon growth or survival rate (p > 0.05). The strontium content in tissues increased with dietary strontium levels, with the highest enrichment in bone plates (p < 0.05). However, muscle crude fat in the strontium-supplemented groups decreased significantly; the Sr160 group had higher glutamic acid, valine, docosahexaenoic acid methyl ester, lower myristic acid, palmitic acid, etc. (p < 0.05). In addition, strontium treatment alleviated hepatic lipid accumulation and mitochondrial swelling. Biochemical analyses revealed reduced plasma levels of Triglyceride (TG), Total Cholesterol (TC), Alanine Aminotransferase (ALT), and Aspartate Aminotransferase (AST), as well as decreased hepatic Malondialdehyde (MDA) content, while hepatic Glutathione (GSH) levels increased (p < 0.05). Transcriptomic data further showed that strontium downregulated the expression of fasn and tfrc and upregulated the expression of cpt1a, apoa1, cyp7a1, and slc3a2 (p < 0.05). In conclusion, dietary supplementation with 80–160 mg/kg strontium enables safe strontium enrichment in hybrid sturgeon, improves muscle nutritional quality, and protects liver function by regulating the genes related to lipid metabolism and antioxidant defense, providing a scientific basis for the development of strontium-enriched fish products.