Effects of crystalline amino acids, phytase and fish soluble supplements in improving nutritive values of high plant protein based diets for kuruma shrimp, Marsupenaeus japonicus

Plant proteins are the most important alternatives to fishmeal in shrimp diets. However, there is a general trend of reducing feed intake and shrimp performance with dietary inclusion of high levels of plant proteins. Supplementation of feed additives could overcome the negative effects of high plant protein based diet. Therefore, an experiment was conducted to assess the effectiveness of different feed additives such as crystalline amino acids (CAA), phytase (PT) and fish soluble (FS) in enhancing the utilization of high levels of plant proteins in the diets of kuruma shrimp, Marsupenaeus japonicus. Six isocaloric diets (19kJg−1) were formulated where diet 1 was 40% fishmeal based control diet (FM). Diets 2 to 6 were prepared as follows, by replacing 60% fishmeal protein with a plant protein blend (soybean meal and canola meal; 6:4) alone (PP); protein blend and 1.5% CAA (PAA); protein blend and 0.04% phytase (2000FTUkg−1) (PPT); protein blend and 10% FS (PFS); and protein blend and a mixture of CAA, phytase and FS (PMX) respectively. Triplicate groups of shrimp (1.75±0.40g; mean initial body weight±SD) were stocked in 54–l rectangular tanks at a rate of 15 shrimp per tank. The tanks were maintained under natural light/dark regime in a flow-through sea water system. Shrimp were fed the respective test diets at a rate of 8–10% of the body weight daily for 56days. At the end of the feeding trial, final body weight (g), weight gain (%) and specific growth rate (%day−1) were significantly (P