Effects of dietary fermented by-product of mushroom, Pleurotus ostreatus , as an additive on growth, serological characteristics and nonspecific immune responses in juvenile Amur catfish, Silurus asotus

Abstract

The present experiment was conducted to evaluate the efficacy of dietary fermented by-product of mushroom, Pleurotus ostreatus, (FBPM) as an additive in juvenile Amur catfish, Silurus asotus. Five diets were formulated to contain 0%, 0.1%, 0.2%, 0.4% and 0.8% (FBPM0, FBPM0.1, FBPM0.2, FBPM0.4 and FBPM0.8 respectively) of FBPM. Fifteen fish averaging 5.7 ± 0.1 g (Mean ± SD) were fed one of the five diets in triplicate groups at 3–4% of wet body weight/day for 8 weeks. Average weight gain (WG) and specific growth rate (SGR) of fish fed FBPM0.1 and FBPM0.2 diets were significantly higher than those of fish fed FBPM0. Hematocrit contents of fish fed FBPM0.2 were significantly higher than that of fish fed FBPM0. Lysozyme activity of fish fed FBPM0.1 was significantly higher than those of fish fed FBPM0, FBPM0.2, FBPM0.4 and FBPM0.8, while chemiluminescent (CL) responses of fish fed FBPM0.2 was significantly higher than those of fish fed FBPM0, FBPM0.1, FBPM0.4 and FBPM0.8. Broken line regression analysis of WG showed that optimum dietary FBPM levels based on WG could be 0.11%. Therefore, these results suggested that the optimum dietary inclusion level of mushroom, Pleurotus ostreatus by-product fermented using lactobacillus and yeast could be greater than 0.11% but less than 0.2% based on WG and immunological responses in Amur catfish, Silurus asotus without any adverse effects on serological characteristics and body composition.