Can sulforaphane alter growth performance, innate immunity and antioxidant capability of common carp (Cyprinus carpio Huanghe var)?

Sulforaphane (SFN) is a plant extract with demonstrated immunity, anti-inflammatory and antioxidant properties. However, its research on aquatic animals is still lacking. Herein, this study aimed to investigate the effects of SFN on growth performance, innate immunity and antioxidant capability of common carp (Cyprinus carpio Huanghe var). Fish (76.17 ± 0.23 g) were fed diets supplemented with five levels (0, 5 mg kg−1, 10 mg kg−1,15 mg kg−1 and 20 mg kg−1) of SFN for 8 weeks. The results indicated that fish fed 10 mg kg−1 SFN showed higher weight gain rate (P < 0.05) than the control group and the group of 15 mg kg−1 SFN. Feed conversion ratio was significantly lower (P < 0.05) in fish fed 10 mg kg−1 SFN than the group of 15 mg kg−1 SFN. Plasma complement component 4 and interleukin-10 (IL-10) contents, acid phosphatase activity, and liver superoxide dismutase, glutathione peroxidase and catalase activities, glutathione content, and interleukin-1β, IL-10, tumor necrosis factor-α (TNF-α) and toll-like receptor 2 mRNA expressions all increased (P < 0.05) in response to dietary SFN levels from 0 to 10 mg kg−1, then decreased with further increasing SFN levels. Plasma TNF-α content increased (P < 0.05) in response to dietary SFN levels from 0 to 15 mg kg−1, then decreased with further increasing SFN levels. Plasma lysozyme and myeloperoxidase activities both increased (P < 0.05) in response to dietary SFN levels from 0 to 5 mg kg−1, then decreased with further increasing SFN levels. Liver malonaldehyde content was significantly lower (P < 0.05) in fish fed 10 mg kg−1 SFN than other groups except for the 5 mg kg−1 SFN. Overall, these findings suggested that dietary SFN could promote growth, enhance immunity and antioxidant capacity, and the best benefit was obtained in fish fed 10 mg kg−1. These results encouraged further research of SFN as feed additive in aquaculture and provided basic data for the future application of SFN in aquatic animals.