Effects of fish meal replacement using an animal and plant protein mixture in diets for juvenile red seabream (Pagrus major)

The experiment was designed to study effects of fish meal (FM) replaced diets containing a mixture of meat meal (MM), chicken byproduct meal (CBM), soy protein concentrate (SPC) and corn gluten (CG) on growth performance, feed utilization, biochemical parameters and muscle composition of juvenile red seabream (Pagrus major). A diet formulated to contain 60% FM was considered as the control (CON). Two other diets were designed by reducing FM levels to 40% and 20% with 5% or 10% of each MM, CBM, SPC, and CG to contain 20% or 40% protein source mixture in each diet (named as MX20 and MX40 respectively). Red seabream in juvenile stage was distributed among nine fiberglass tanks having a capacity of 300 L. Average weight of fish was 4.57 g and each tank was added with 40 fish assigning as one of three replicates of diets. Fish were fed till satiation two times a day at 09:00 and 17:00 h for eight weeks. Growth performance of fish fed CON and MX20 diets were significantly higher than those of fish fed MX40 diet. Feed intake of fish in CON group was significantly higher compared to MX40 group. Feed utilization was not significantly affected due to FM replacement with protein sources. Serum lysozyme and superoxide dismutase activities were not significantly different among dietary treatments. Plasma triglyceride level was significantly higher in fish fed CON diet compared to that of MX40 group. Muscle proximate and amino acid compositions were not significantly affected by the dietary treatments. Muscle palmitic acid level was significantly lower in CON group while dihomo-gamma-linolenic acid was significantly higher compared to MX20 and MX40 groups. Therefore, the mixture of MM, CBM, SPC, and CG can be used to reduce FM from red seabream diets to 40% without negative influences on growth performance compared to a diet containing 60% FM. FM level can be further reduced to 20% with the ingredient mixture without compromising feed utilization, innate immunity and muscle quality.