Effects of dietary supplementation with different aquatic weed meals on the growth performance, digestive enzyme and antioxidant enzyme activities, and coloration of Procambarus clarkii

In order to study the effect of the diet supplemented with different aquatic weed meals on growth performance, digestive enzyme activity, antioxidant enzyme activity and coloration of Procambarus clarkii, five kinds of aquatic weed meals were added into diet at the level of 15% separately (Diet 2-6), including Elodea nuttallii, Hydrilla verticillata, Vallisneria natans, Ceratophyllum demersum and Alternanthera philoxeroides. The control group (Diet 1) did not contain aquatic weed meals. The six diets were fed to juvenile Procambarus clarkii for 60 days. The results showed that there was no significant difference in survival rate (SR) between Diet 2-6 and Diet 1. The weight gain rate (WGR) and specific growth rate (SGR) in Diet 3-5 were not significantly different from those of Diet 1, and the hepatopancreas index (HSI) of Diet 3 was significantly higher than that of Diet 1. Moreover, in hepatopancreas, the lipase (LPS) activity of Diet 2-6 were significantly higher than Diet 1, LPS and α-amylase (α-AL) activities of Diet 5 were the highest, and the pepsin activity was the highest in Diet 2. The cellulase (CL) activity in Diet 2-3 and 5 were significantly higher than Diet 1. The activities of 4 digestive enzymes in Diet 2-6 were lower than Diet 1 in intestine. The content of total carotenoids in carapace, muscle and ovary, the astaxanthin in carapace and ovary, the lutein and β-carotene in ovary of Diet 3-6 were significantly higher than those of Diet 1. The redness value (a*) and yellowness value (b*) of all treatment groups were significantly higher than Diet 1 in carapace and ovary, while lightness value (L*) was lower. The antioxidant capacity in hepatopancreas, the total superoxide dismutase (T-SOD) activity of Diet 2-6 was significantly higher than Diet 1 and Diet 5 was the highest. The total antioxidant capacity (T-AOC) activity of Diet 4 was the highest while the highest malondialdehyde (MDA) content was found in Diet 2. In serum, Diet 6 had the highest T-AOC activity, and no significant difference was found in T-SOD activity and MDA content between Diet 1-6. In conclusion, diet supplemented with 15% H. verticillata, V. natans, C. demersum meals could meet the growth requirements of P. clarkii, improve the coloration of carapace and ovary, and promote the health status of P. clarkii.