Replacement of fish meal by enzyme‐treated soybean on the growth performance, intestine microflora, immune responses and disease resistance of Pacific white shrimp Litopenaeus vannamei

An 8-week feeding trial was conducted to investigate the effects of replacing dietary fish meal with enzyme-treated soybean (ETS) on the growth performance, intestine microflora, immune response and disease resistance of white shrimp, Litopenaeus vannamei (initial body weight: 1.5 ± 0.2 g). With fish meal was replaced by 0%, 8%, 16%, 24%, 32%, 40% and 48% of the ETS, respectively, seven isonitrogenous experimental diets were formulated. These diets were named as Diet-0, Diet-8, Diet-16, Diet-24, Diet-32, Diet-40 and Diet-48 respectively. Results showed that the survival rate (SR) and specific growth rate (SGR) of shrimp had no significant difference among all the groups (p > 0.05). When the replacement level was up to 48%, the feed conversion ratio (FCR) increased significantly. Both the total anti-oxidative capacity (T-AOC) and malondialdehyde (MDA) contents in serum were increased with replacement levels. The highest values for T-AOC and MDA were found as 0.49 mM and 9.17 nmol/ml in the Diet-32 and Diet-24 group respectively. Activity of lysozyme in serum increased with replacement levels from 8% to 40%. Proteobacteria, Bacteroidetes, Actinobacteria, Tenericutes and Firmicutes were the major phyla found in the intestine of shrimp. After the challenge test, there were no significant negative effects on the survival rate of shrimp. In conclusion, in regard to SGR of shrimp, the replacement level of dietary fish meal by ETS can be up to 48%. For the FCR, the replacement level can be up to 16%.