Effects of dietary astaxanthin supplementation on juvenile kuruma shrimp, Marsupenaeus japonicus

This study evaluated the effects of chemically synthesized astaxanthin (Ax) on growth performance, survival, stress resistance, immune responses, fatty acid contents, and pigmentation of juvenile kuruma shrimp (Marsupenaeus japonicus). Six dietary levels of Ax (0, 200, 400, 800, 1200, and 1600 mg kg(-1) diet) were added to a baseline diet. The feeding trial was conducted for 56 days. The results showed that juveniles fed diets supplemented with Ax exhibited better growth performance, final body weight (FBW), body weight gain (BWG), and specific growth rate (SGR) than the control group, with the best performance exhibited by in the 400 mg kg(-1) diet Ax supplemented group (P < 0.05). Following fresh water-osmotic stress test, the 200, 400, and 800 mg kg(-1) diet Ax supplemented groups showed higher LT50 values than the other groups. The 400, 800, and 1200 mg kg(-1) diet Ax supplemented groups exhibited different immune responses (total hemocyte count [THC] and viable cells [VC]) to the control group. The Ax content of the whole shrimp body increased with increasing supplemented levels. After cooking, shrimp fed diets containing Ax were a strong red in color, while the control group was light pink in color. The colorimetric reading of the body and head of cooked shrimp showed that redness (a*) and yellowness (b*) increased with increasing dietary Ax supplementation. The 1200 and 1600 mg kg(-1) diet supplemented groups were also significantly different from the control group for these two parameters in both shrimp body and head. Broken-line regression analysis indicated that the optimal levels for growth, immune responses, and pigmentation were 401, 420, and 404 mg kg(-1) diet, respectively. In conclusion, the optimum diet supplementation level of the Ax to enhance the performance of juvenile kuruma shrimp is around 400 mg kg(-1).