Growth and apparent digestibility of nutrients, fatty acids and amino acids in Pacific white shrimp, Litopenaeus vannamei, fed diets with rice protein concentrate as total and partial replacement of fish meal

Growth and apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), crude lipid (CL), gross energy (GE), essential amino acids (EAA), nonessential amino acids (NEAA) and fatty acids (FA) were determined for the Pacific white shrimp, Litopenaeus vannamei. Five isonitrogenous (36.6% protein) diets, formulated by replacing 0, 25, 50, 75, and 100% of fish meal (FM) with rice protein concentrate (RPC), were fed to shrimp (initial weight 6.99 ± 0.08 g) five times daily to satiation for 60 days. ADCs were determined using 0.5% Cr2O3. Feces were collected from three replicate groups of shrimp. Shrimp fed with 0, 25 and 50% replacements had similar weight increase (P < 0.05), specific growth rate (SGR) and feed conversion ratio (FCR), whereas all the above parameters declined significantly (P < 0.05) as the dietary RPC levels increased above 50%. Survival was high (≥ 95%) and similar for all diets. ADCs of diets were: CP (52.41–90.52%), CL (80.03–94.11%), GE (55.24–89.41%), EAA (57.39–96.13%), NEAA (41.11–94.74%), SFA (24.61–65.43%), MUFA (41.50–80.45%), and PUFA (57.14–83.90%). Generally, a decreasing trend in ADC for crude protein, crude lipid, gross energy and amino acid (AA) was observed when the RPC level increased. ADC of the FA in shrimp fed with FM and 50% RPC were significantly higher than 25, 75 and 100%. The highest digestibility values were obtained in the FM diet (P < 0.05). The results suggest that RPC can be a potential candidate for FM replacement up to 50%; reduced growth performance was mostly a consequence of reduced digestible nutrients as the RPC level was increased in the diet.

► RPC can be used with an inclusion level of up to 50% in L. vannamei diet.
► Replacing above 50% inclusion resulted in an almost linear reduction in the ADCs of the nutrients.
► ADCs data clearly indicate that RPC has a lower digestibility than FM.
► Lower digestibility of RPC may have brought about regressed digestible protein to growth as the RPC substitution increases above 50%.
► The higher inclusion of less costly plant proteins (RPC) will bring about less inclusion of costly FM in the feed formulations.