Partial replacement of fish meal by soybean meal supplemented with inulin and oligofructose in the diet of pikeperch (Sander lucioperca): Effect on growth and health status
Authors: Dadras Hadiseh , Chupani Latifeh , Imentai Aiman , Malinovskyi Oleksandr , Esteban Maria Angeles , Penka Tomas , Kolářová Jitka , Rahimnejad Samad , Policar Tomáš 
Published: October 2022

The present study investigated the effect of partial substitution of soybean meal (SM) for fish meal (FM) with or without addition of inulin and oligofructose in pikeperch feed. A diet containing FM was considered as the basal diet, and then three other diets were prepared by: 1) replacing 50% of FM with SM (SM50), 2) replacing 50% of FM with SM and supplementation of 2% inulin (SMI50), and 3) replacing 50% of FM with SM and supplementation of 2% oligofructose (SMO50). Each diet was fed twice daily to triplicate groups of fish (36.68 ± 0.36 g) for eight weeks. The group fed SMO50 showed the highest weight gain (WG; 85.85 ± 4.46%) among the groups fed SM, with no significant difference from the FM group (79.74 ± 2.04%; p &gt; 0.05). Specific growth rate (SGR) showed no significant differences among fish fed SMI50 (0.81 ± 0.07%), SMO50 (1.01 ± 0.09%) and FM (1.05 ± 0.02%). However, a lower SGR (0.69 ± 0.09%) was observed in the SM50 group without the supplementation of 2% inulin or oligofructose compared to the group fed FM (p &lt; 0.05). The groups fed SMI50 and SMO50 showed no significant difference in FCR (1.23 ± 0.10; 0.91 ± 0.05, respectively) compared to the group fed FM (0.97 ± 0.04). While, a significant difference in FCR was found between the SM50-fed group without supplementation of inulin or oligofructose (1.50 ± 0.13) and the group fed FM (0.97 ± 0.04). Survival rate and whole-body composition showed no significant difference among all groups (p &gt; 0.05). A significant decrease in serum total cholesterol concentration was observed in the SMO50 group (2.10 ± 0.29 mmole L-1) compared to the FM-fed group (3.33 ± 0.33 mmole L-1). Serum triglyceride showed a significant decrease in the groups fed SMI50 (0.98 ± 0.17 mmole L-1) compared to the group fed SMO50 (1.93 ± 0.24 mmole L-1). The concentrations of other serum biochemical parameters (total protein, glucose, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase) were not significantly affected by the dietary treatments (p &gt; 0.05). Among all innate immunity and antioxidant parameters, only the serum malondialdehyde (MDA) concentration of SM50-fed fish (4.25 ± 0.7 nmole mL−1) was significantly lower than in the FM-fed group (with the highest MDA concentration; 25.17 ± 3.13 nmole mL−1). Serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT) were not significantly affected by the feeding (p &gt; 0.05). Serum D-lactate concentration was not significantly affected by the dietary treatments (p &gt; 0.05). No significant differences were found in the relative expression of IGF-I, IGF-II, GHR genes among the studied groups (p&gt; 0.05). The results of the present study show that 50% replacement of FM with SM supplemented with a small amount of oligofructose (2% of dry matter) does not compromise the growth performance or the immune system of pikeperch. This substitution is feasible and provides a reference for cost-optimized design of feed formulation for pikeperch.