An 8‐week feeding trial was conducted to evaluate the effects of replacing fishmeal by concentrated dephenolization cottonseed protein (CDCP) on growth, feed utilization, body composition, haemolymph indexes and antioxidative ability of juvenile white shrimp Litopenaeus vannamei, Boone. Six practical diets CDCP0, CDCP50, CDCP100, CDCP150, CDCP200 and CDCP250, containing a gradient of CDCP 0g/kg, 50g/kg, 100g/kg, 150g/kg, 200g/kg and 250 g/kg) to substitute (50g/kg, 90g/kg, 130g/kg, 170g/kg, 210g/kg and 250 g/kg) of fishmeal, diets were fed to four replicate groups. Amino acids were supplemented in the low fishmeal diet to obtain similar amino acid profile as the control diet. The results indicated that shrimp fed the CDCP20 and CDCP25 diet had poor growth performance and feed utilization compared with the CDCP0 group. No difference was observed in body composition among all the treatments. Total cholesterol (T‐CHO), high‐density lipoprotein cholesterol (HDL‐C) and low‐density lipoprotein cholesterol (LDL‐C) concentrations in haemolymph were significantly lower in high‐CDCP groups. The digestibility of protein decreased significantly with increasing CDCP levels. When shrimp fed the CDCP250 diet had the significant lower total antioxidant capacity (T‐AOC) and catalase (CAT) activity than control diet. In conclusion, fishmeal can be reduced from 250g/kg to 130 g/kg by CDCP.

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A 10‐week growth trial was run to evaluate effects of myo‐inositol (MI) on growth performance, haematological parameters, antioxidative capacity and salinity stress tolerance of Litopenaeus vannamei. Six practical diets supplemented with graded levels of MI (designated as MI0, MI600, MI1200, MI2400, MI 3600 and MI4800 for 448.8, 974.2, 1568.0, 2810.6, 3835.5 and 4893.6 mg/kg diet, respectively) were fed to six replicate groups of L. vannamei (mean initial body weight 0.63 ± 0.00 g). The results showed that significant increment of growth performance was observed in shrimp fed MI600 diet than those fed MI1200 diet. Lipid concentration in whole body of the shrimp fed MI600 diet was significantly increased. Shrimp fed MI0 diet had lower total protein (TP) as compared to shrimp fed the MI‐supplemented diets (except MI4800 diet). In general, lower activities of antioxidant enzymes and higher malondialdehyde (MDA) content in haemolymph and hepatopancreas were recorded in shrimp fed MI0 diet, compared to those fed the MI‐supplemented diets. Reduced survival after 7‐h salinity stress was present in shrimp fed MI0 diet as compared to those fed MI4800 diet. Dietary MI requirement for glutathione peroxidase activity of L. vannamei was 2705 mg/kg diet.

A 25‐day experiment was conducted to evaluate the optimal lipid level for postlarval Litopenaeus vannamei. Shrimp (1.7 mg) were fed five isonitrogenous diets containing grade levels of lipid (96.6, 114.3, 128.5, 136.5 and 154.5 g/kg diet, respectively). Each diet was assigned to four tanks (500 shrimp), and shrimp were fed six times a day. Weight gain was increased with the increasing dietary lipid levels, and the highest weight gain was observed in shrimp fed diet with 154.5 g/kg lipid (p < 0.05). On the contrary, the survival was lowest in shrimp fed the L15.45 and highest in shrimp fed the L11.43. Triglyceride in hepatopancreas was increased, and cholesterol was decreased with the increasing dietary lipid. Pyruvate kinase and AMPK mRNA expression were highest in shrimp fed the L12.85. Malondialdehyde in whole body was positively correlated with the dietary lipid levels. The mRNA expression of SOD and Caspase 3 was highest in shrimp fed the L12.85. After hypoxia stress, shrimp fed the L12.85 showed highest survival. The mRNA expression of superoxide dismutase and Akirin was highest in shrimp fed the L11.43 and L15.45, respectively. Based on the survival after 25‐day feeding trail and after the hypoxia stress, the optimal dietary lipid for postlarval L. vannamei should be 118–124 g/kg.

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