Effects of graded dietary raw bee venom inclusion on growth, immunity, and disease resistance in Nile tilapia (Oreochromis niloticus)

Abstract Nowadays, studies on the application of bee venom (BV) in aquaculture have been growing due to its bioactive constituents. However, previous studies have focused on nano-formulated bee venom or parenteral administration routes on Nile tilapia ( Oreochromis niloticus ). However, the effects of graded dietary supplementation of raw venom, especially at different inclusion levels, on Nile tilapia are still limited. Therefore, this study focused on investigating the effects of bee venom supplementation at different dosage levels on growth performance, hematological and biochemical parameters, antioxidant status, immune responses, immune-related gene expression, disease resistance against Aeromonas sobria , and economic efficiency. One hundred and eighty Nile tilapia were randomly assigned to 4 dietary groups (CONT, BV4, BV8, and BV12) with 3 replicates for each group. The CONT group received a basal diet. The BV4, BV8, and BV12 groups administered bee venom in their diet at 4, 8, and 12 mg/kg, respectively. The growth performance was significantly improved with increasing BV inclusion ( P  ≤ 0.005), with final body weight increasing from 49.16 g in CONT to 61.96 g in BV12, while FCR decreased from 1.75 to 1.43. Hematological parameters were improved in BV8 and BV12 groups, where hemoglobin concentration increased from 9.39 g/dl in CONT to 12.28 g/dl and white blood cell count increased from 6.08 × 10 3 / µl to 7.98 × 10 3 / µl, respectively ( P  ≤ 0.015). Liver enzymes (ALT and AST) and stress indicators (glucose and cortisol) did not differ significantly among all the dietary groups. When the concentration of BV increased, the activities of digestive enzymes, antioxidant status, and innate immunity were significantly promoted, along with remarkable upregulation in mRNA levels of TNF-α , IL-1β , and IL-10 . Dietary bee venom supplementation (8 and 12 mg/kg) exhibited a marked histological improvement of intestinal tissues when compared with the control group. Following the challenge with A. sobria , cumulative mortality progressively decreased from 53.33% in the challenged CONT group to 26.66%, 13.33%, and 6.66% in BV4, BV8, and BV12, respectively. The economic analysis showed higher profit per gram of weight gain in the BV12 and BV8 groups without increased feed cost. The BV12 group showed the highest profit per gram of weight gain (0.0839 ± 0.001) compared to the control (0.0589 ± 0.002) ( P  < 0.001). In summary, dietary supplementation with BV, especially in 12 mg/kg under the conditions of the present study, significantly improved growth, feed utilization, immune responses, and disease resistance. Therefore, 12 mg/kg can be considered the best-performing tested level of BV, and further investigations are warranted to evaluate raw bee venom as a potential functional feed additive in Nile tilapia.