OPTIMUM SUPPLEMENTATION OF ASTAXANTHIN FOR KURUMA SHRIMP Marsupenaeus japonicus  

Astaxanthin (Ax) as an important pigment source and antioxidant is considered that it is necessary to be provided in the diet for cultured shrimp. But the optimum supplemental amount to diets for larval, post-larval and juvenile kuruma shrimp are still unrevealed.

Three individual trials were conducted on to evaluate the effect of chemically synthesized Ax (Carophyll Pink^Ⓡ) on growth performance, survival, stress resistance, colorimetric reading, Ax contents determination and immune response, respectively.

Six dietary levels of Ax (0, 50, 100, 200, 400 and 800ppm per kg diet) were added to the micro-bound diet (MBD) and fed to triplicate groups of kuruma shirmp. Firstly, 8-day feeding trial was conducted to investigate the effectiveness of dietary supplementation of Ax on survival (SR), growth, developmental stage (DS), metamorphosis to post-larval (PL) and formalin stress resistance (LT₅₀) on larval kuruma shrimp. The obtained results showed that shrimps fed diets supplemented with Ax exhibited higher SR, DS PL, TL and LT₅₀ values significantly in dose dependent manner with the highest being in case of 200 ppm supplemented group (P<0.05).

Then, the second study was conducted to evaluate the effect of dietary Ax on the performances of post-larval kuruma shrimp for 30 days. Shrimps fed diets containing Ax showed higher final body weight (FBW), weight gain (WG) and specific growth rate (SGR) compared to the control group with the highest being in case of 100 and 200 ppm supplemented groups (P<0.05), however, no significant differences were detected in the other groups. After formalin stress test (LT₅₀), the data showed that LT₅₀ was significantly higher in case of 100 and 200 ppm supplemented groups than the control group (P<0.05). Furthermore, the data of cumulative mortality index (CMI) for osmotic stress showed significantly lower values than the control group (P<0.05) with the lowest value in case of 200 ppm group.

Thirdly, another six dietary levels of Ax (0, 200, 400, 800, 1200 and 1600 ppm per kg diet) were added to the pellet diet and fed to triplicate groups of juvenile kuruma shrimp for 56 days. Shrimp fed diets containing Ax showed higher final body weight (FBW), weight gain (WG) and specific growth rate (SGR) compared to the control group with the highest being in case of 400 and 800ppm supplemented groups (P<0.05). After formalin stress test (LT₅₀), the 200, 400 and 800ppm supplemented groups showed higher data than other groups. After cooking, shrimp fed the diets containing the Ax exhibited a strong red color compared to the light pink color of control group. Colorimetric reading in cooked shrimp and Ax content for whole shrimp body demonstrated that pigmentation was increased in kuruma shrimp fed diets with increasing Ax levels in current study.

We concluded from the current studies that Ax was a necessary ingredient for kuruma shrimp. Considering the effect of Ax on comprehensive performance, the level of Ax supplemented in the diet for larval and post-larval kuruma shrimp should be between 100 and 200 ppm, and for juvenile kuruma shrimp should range from 400-800 ppm.