EFFECTS OF FOUR COMMONLY USED PLANT PROTEIN SOURCES ON GROWTH PERFORMANCE, AMINO ACIDS RETENTION AND ANTIOXIDANT ENZYME ACTIVITIES IN JUVENILE CHINESE MITTEN CRAB, ERIOCHIER SINENSIS

Chinese mitten crab (Eriocheir sinensis) is an importantly economic species for aquaculture in China due to its desirable taste and nutrient content. In the past decades, with the continuous expansion of crab farm and artificial feed development, the increasing demand for fish meal by aquaculture industry makes fish meal an increasingly expensive and limiting commodity. This study investigated the effects of dietary partial replacement of fishmeal (FM) by four commonly used plant protein sources on juvenile Chinese mitten crab, with a basic diet containing 50% fishmeal as the control, and other four diets with 50% fishmeal replaced by 30.50% fermented soybean meal (FSBM), 32.50% soybean meal (SBM), 28% cottonseed meal (CSM), and 39% rapeseed meal (RSM). Each diet was fed to four replicates of juvenile E. sinensis (0.249±0.003 g) for 8 weeks. The results showed that no differences were found in weight gain, specific growth rate, feed conversion ratio, protein efficiency, and protein retention when compared crab fed the three test diets (FSBM, SBM, CSM) with the FM diet. The weight gain of E. sinensis fed RSM was not different from crab fed FM, but was lower than crab fed SBM (P < 0.05). Feed conversion ratio of E. sinensis fed RSM was higher than those fed FM, FSBM and SBM. Protein efficiency of E. sinensis fed RSM was lower than all other groups (P < 0.05). Protein retention of E. sinensis fed RSM was lower than crab fed SBM or CSM (P < 0.05).No differences were found in the contents of the whole crab body moisture, ash, crude lipid, and total essential amino acid retention rate of the four plant protein sources groups relative to the FM group. However, the whole crab crude protein content of crab fed RSM was lower than crab fed SBM or CSM (P < 0.05). The total essential amino acid retention of crab fed RSM was lower than crab fed FSBM or CSM (P < 0.05). Superoxide dismutase and glutathione peroxidase activities in both serum and hepatopancreas of crab were not different when compared the groups of the four plant protein sources with the FM group. The serum malonaldehyde content of crab fed RSM was higher than crab fed all other diets (P < 0.05). The results indicates that partial replacement of fish meal with FSBM, SBM or CSM will not lead to any negative effects on growth performance, amino acid retention and antioxidant enzyme activities in juvenile Chinese mitten crab. Thus, FSBM, SBM or CSM can be used as alternative plant protein sources to replace fishmeal in diet for Chinese mitten crab up to 30%. However, rapeseed meal is not a suitable protein source due to the lower protein digestibility, anti-nutritional factor contents. In case where rapeseed meal must be used in the diet of E. sinensis, it should be used in combination with other plant protein sources, and adequate process should be conducted to lower contents of the anti-nutritional factors.