Abstract
This study was conducted to investigate the effects of replacing fishmeal (FM) with Chlorella sorokiniana on growth and flesh quality of Pacific white shrimp, Litopenaeus vannamei. A control diet was formulated to contain 560 g/kg FM, and then chlorella meal was used to replace 0% (C-0), 20% (C-20), 40% (C-40), 60% (C-60), 80% (C-80), and 100% (C-100) of dietary FM, respectively. The six isoproteic and isolipidic diets were fed to shrimp (1.37 ± 0.02 g) for 8 weeks. The results showed that weight gain (WG) and protein retention (PR) of C-20 group were significantly higher than those of C-0 group (P < 0.05), while no significant differences were observed in WG and PR between C-0 and C-40 groups (P > 0.05). When the replaced level of FM by chlorella meal reached 60%, the WG of shrimp decreased and feed conversion ratio (FCR) increased significantly (P < 0.05). The quadratic regression analysis indicated that substituted fishmeal levels with chlorella meal were 20.50% and 28.25%, respectively, to obtain the highest WG and lowest FCR. In C-40 and C-60 groups, the body surface presented higher redness than the control (P < 0.05). No significant differences in the whole body and muscle composition, SOD, T-AOC, GSH-PX activities, MDA contents, total collagen content, steaming loss, texture property, free delicious amino acids contents, PUFAs, and n-3/n-6 PUFAs in flesh were observed among the three groups of C-0, C-20, and C-40 (P > 0.05). Compared to the control group, C-60, C-80, and C-100 groups showed lower flesh hardness, chewiness, shear force, and higher steaming loss and resilience (P < 0.05). There were no significant differences in serum TP, TG, GLU, and ALB contents, boiling loss, freezing loss, total free amino acids, SAFs and MUFAs among all the groups (P >0.05). Conclusively, in a diet containing 560 g/kg FM, chlorella meal could replace 40% dietary FM without negative effects on the growth and flesh quality, while increase the body redness of white shrimp.