Effects of small size-fractionated fish protein hydrolysate substitution of fish meal in high plant protein diets on the growth performance and non-specific immunity of Japanese flounder, Paralichthys olivaceus

Abstract:

A 63-day feeding experiment was conducted to evaluate the effects of fish protein hydrolysate as feed ingredient in high plant-protein diets on growth performance and non-specific immunity for Japanese flounder, Paralichthys olivaceus. Fish protein hydrolysates respectively replaced 0 (FM1, negative control， containing 55% soybean meal and 19% fish meal), 0(FM2，positive control， containing 45% soybean meal and 25% fish meal), 6% (FPH6), 11% (FPH11), 16% (FPH16), 21% (FPH21),and 26% (FPH26)of the total protein. The results showed that specific growth rate and protein retention of fish fed with FPH11 was significantly higher than FM1（P<0.05），but was not significantly different from FM2（P>0.05）. For protein digestibility, all the hydrolyzed protein diets were significantly higher than FM1（P<0.05），but was not significantly different from FM2（P>0.05）. Feeding rates of FPH11，FPH16，FPH21 and FPH26 were significantly higher than FM2（P<0.05）. The relative activities of acid phosphatase (ACP) in fish fed with FM1 was significantly lower than FPH26（P<005）. SOD relative activities in all the hydrolyzed protein diet were higher than FM1（P<0.05）, and SOD relative activities in FPH11 was significantly higher than FM2（P<0.05）. Total antioxidative capacity of FPH6, FPH11 and FPH16 were significantly higher than FM1 and lower than FM2（P<0.05）.