Effect of β-Glucan on cold-stress resistance of striped catfish, Pangasianodon hypophthalmus (Sauvage, 1878)

These experiments were performed to determine the effects of dietary beta-glucan on stress responses of striped catfish (Pangasianodon hypophthalmus). Fish were fed for nine weeks with a diet containing 0 (control), 0.5% (G1), 1% (G2) and 2% (G3 group) beta-glucan. Subsequently, stress responses were studied by evaluating serum cortisol and glucose levels following a constant 24 h cold shock (from 28 degrees C to 15 degrees C). Serum cortisol and glucose concentrations were measured after cold treatments of varying durations (prior to, and after one, 12 and 24 h of cold shock stress, respectively). No differences in serum cortisol and glucose levels were found between control and beta-glucan-treated fish. However, the mortality rate was significantly lowered in cold challenged fish fed appropriate doses of beta-glucan (in G1 and G2 vs. G3 and control group). The results of the present study demonstrate that a proper administration of beta-glucan in the diet could ameliorate the detrimental effects of a severe stress resulting in a reduction in fish mortality.