Effects of diets with fermented duckweed (Lemna sp.) on growth performance and gene expression in the Pacific white shrimp, Litopenaeus vannamei

This study evaluated the effects of diets with fermented duckweed flour (Lemna sp.) (FDF) on growth performance and gene expression in Pacific white shrimp, Litopenaeus vannamei. Shrimp were cultured in an outdoor system during 50 days and fed diets containing 0, 5, 15, 25, and 35 % FDF replacing fishmeal (FM) (diets D0, D5, D15, D25, and D35, respectively). At the end of the bioassay, shrimp survival was 100 % in all treatments and growth performance was significantly better than D0 (100 % FM), especially in diet D35 with 35 % FDF. The mRNA expression of trypsin, chymotrypsin, cathepsin B, heat shock protein 70 (Lvhsp70), and heat shock protein 90 (Lvhsp90) was significantly increased at the highest FDF concentrations in diets (D15, D25, and D35) as compared to D0. Dietary FDF affected the immune system of shrimp only in diets D5 (superoxide dismutase and lysozyme) and D15 (lysozyme) where mRNA expression was significantly higher than D0. FM can be replaced with up to 35 % FDF without adversely affecting the survival and growth performance of cultured shrimp. The inclusion of FDF in diets affected the expression of stress and digestive genes, but, in immune-related genes, the effect did not show a clear trend.