After the 27th day, the THC, superoxide anion and SOD activity in haemolymph of shrimps fed with β-glucanwere no longer significantly higher (PN0.05) than those in the control group.However, the activity of PO in β-glucan group (0.69±0.04 U) was significantly higher (Pb0.05) than that in the control group (0.55±0.04 U) even on the 33rd day.