Values of THC (9.03±0.45×106 cells ml−1, mean±S.D.) and PO activity (0.62±0.07 U) of the shrimps fed with β-glucan continuously were significantly higher (Pb0.05) than those in the control group (7.35±0.27×106 cells ml−1 and 0.44±0.08 U, respectively) on the 5th day (Tables 3 and 4).