Effects of replacing soybean meal with cottonseed meal on growth, feed utilization and non-specific immune enzyme activities for juvenile white shrimp, Litopenaeus vannamei

Cottonseed meal (CSM) was evaluated as a protein source for partial replacement of soybean meal (SBM) with iron supplementation in diets of juvenile Litopenaeus vannamei. In the control diet (DO), SBM protein was replaced with increasing dietary levels of CSM (0 %, 9.2 %, 15.2 %, 21.3 %, 27.4 %, and 30.4 %) at 0 %, 30 %, 50 %, 70 %, 90 %, and 100 % levels (D0 to D100, respectively) with ferrous sulfate supplementation at level of 0 %, 0.04 %, 0.08 %, 0.1 % and 0.12 %, respectively. An eight-week feeding trial was conducted on shrimp (0.383 +/- 0.000 g). Up to 90 % of SBM could be replaced with CSM without causing a significant decrease (P < 0.05) in growth and feed utilization in L. vannamei. Related whole-body composition indexes (moisture, crude protein, crude lipid, ash) were significantly affected with the CSM level in the diets increased (P < 0.05). Regarding serum non-specific immune enzymes, phenoloxidase, acid phosphatase and alkaline phosphatase activities of shrimp were significantly decreased (P < 0.05) with the CSM level in the diets increased. Glutathione peroxidase activity was the highest in shrimp fed the D50 diet, and significantly higher than D0 group (P < 0.05). Total-superoxide dismutase of shrimp fed D90 and D100 diets were significantly lower than that of shrimp fed other diets, whereas malondialdehyde content was significantly higher in the D90 and D100 diets than in the other dietary treatments. Based on the findings in changes in growth and feed utilization, this study found that the optimum ratio is to replaced 87.44 % of SBM with 26.82 % CSM in L. vannamei feed.