Effects of magnetic treatment on growth and immune and digestive enzyme activity in the juvenile sea cucumber Apostichopus japonicus (Selenka)

Recently, magnetic biological technology is gradually applied in aquaculture for enhancing growth, speed of breeding, reducing seedling mortality, increasing immunity and breeding production. We evaluated the effect of duration of exposure and intensity of a stationary magnetic field on growth and immune and digestive enzyme levels in juvenile sea cucumbers, Apostichopus japonicus. Sea cucumbers were exposed to a 0.5 T, 0.3 T, or 0.1 T field for 0.5 or 1 h every 3 d. The weight gain rate (WGR) and specific growth rate (SGR), coelomic levels of lysozyme (LZM), superoxide dismutase (SOD), acid phosphatase (ACP), and alkaline phosphatase (AKP) and intestinal tissue levels of pepsin, trypsin, amylase, and lipase were significantly higher after 60 d in the group exposed to 0.5 T for 1 h when compared with the control group (P < 0.05). Thus, magnetic treatment had a positive effect on growth, immune status, and digestive enzyme levels in juvenile sea cucumbers. Our results provide insight into the utility of magnetic treatment during sea cucumber culture.