An Evaluation of Replacing Fishmeal with Chlorella Sorokiniana in the Diet of Pacific White Shrimp (Litopenaeus Vannamei): Growth, Body Color, and Flesh Quality

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 ( $1.37\pm 0.02$  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.