The prospective utilization of insects as alternative protein sources to replace fishmeal (FM) in aquafeed has prompted increased interest. This study evaluated the effects of yellow mealworm Tenebrio molitor (TML)‐based diet supplemented with 2% mixed probiotics on growth performance and resistance to Aeromonas hydrophila infection in Nile tilapia (Oreochromis niloticus). Six experimental diets were formulated. The control group (CTRL) received commercial feed containing 30% FM. In the experimental groups (T25P+, T50P+, and T100P+), FM was replaced with TML at inclusion rates of 25%, 50%, and 100%, respectively. The T50P– group was identical to the T50P+ group but lacked probiotics, whereas the CTRLP+ group received the control diet (without TML) supplemented with 2% probiotics. Juvenile tilapia weighing 12.81 ± 1.37 g were fed the respective diets for 8 weeks. By the end of the feeding trial, fish receiving the T50P+ diet exhibited superior overall performance, characterized by a significantly higher weight gain (WG; 91%) and survival rate (98%) compared with the CTRL (p < 0.05). This group also demonstrated markedly enhanced digestive enzyme activities, including protease (30.5–34.7 U/mg), lipase (18.2–22.6 U/mg), and amylase (20.8–23.5 U/mg), alongside elevated lysozyme activity, improved antioxidant capacity, and stronger bactericidal activity. Although the T100P+ diet led to improvements in several parameters relative to the control, its overall performance remained inferior to that of the T50P+ group, indicating that partial replacement of FM was more effective than complete substitution. Furthermore, fish fed the T50P+ diet displayed enhanced fillet quality, evidenced by higher crude protein (CP) content (59.63%) and a moderate lipid level (29.73%). Following challenge with Aeromonas hydrophila, the T50P+ group showed a substantially reduced mortality rate (20%) compared with the CTRL (80%), confirming a pronounced improvement in disease resistance. Overall, the results suggest that replacing 50% of FM with TML in combination with probiotics enhances growth, nutrient utilization, immune function, and pathogen resistance in Nile tilapia. This TML–probiotic formulation represents a promising, sustainable, and effective alternative to conventional aquafeeds.
S. Elayaraja, V. Stejskal, Raja Subramaniyan et al.· Aquaculture Nutrition· 0 citations
Bacterial diseases caused by Flavobacterium covae (Fc), Vibrio harveyi (Vh), Vibrio vulnificus (Vv) and Photobacterium damselae (Pd) seriously constrain Asian seabass aquaculture. Here we dissect the mucosal immune mechanisms engaged by a five-month sequential vaccination strategy that combines nanoemulsion immersion priming with multivalent oral hydrogel boosting. Juvenile seabass were vaccinated, then challenged with F. covae by freshwater immersion and with a Vibrio–Photobacterium (Vh/Vv/Pd) mix by immersion or intraperitoneal injection. Gills were sampled after immersion challenges and intestine after injection, and profiled by RNA sequencing and label-free quantitative proteomics, with selected genes validated by RT-qPCR. Principal component analysis showed clear separation of vaccinated and control fish in all tissues and challenges, indicating a strong and coherent transcriptional reprogramming. Vaccination markedly increased the number of upregulated genes, with Gene Ontology enrichment revealing dominant signatures of ribosome biogenesis, RNA processing, lysosomal organization and immune response. KEGG analysis highlighted cytokine receptor interaction; NOD and Toll-like receptor signaling; oxidative phosphorylation; and phagosome, lysosome and cell adhesion molecule pathways, consistent with heightened antimicrobial readiness. Volcano plots and focused heatmaps showed strong induction of interferon-stimulated genes, cytokines and chemokine receptors, complement components, macrophage mannose receptor, epithelial barrier mediators and numerous immunoglobulin transcripts, with tissue- and challenge-specific patterns. Proteomics corroborated these trends, demonstrating a higher abundance of immunoglobulin heavy chains, complement proteins, cathepsins, heat shock and redox chaperones, ribosomal proteins and cytoskeletal and adhesion regulators in vaccinated mucosae. Integrated pathway mapping linked endothelial adhesion molecules and leukocyte integrins with T cell costimulation networks and an intestinal immune network for immunoglobulin production, including enhanced pIgR-mediated transcytosis. Overall, the sequential vaccination regimen was associated with coordinated transcriptomic and proteomic signatures related to epithelial responses, innate immunity, and humoral immune functions across gill and intestinal tissues. These molecular patterns were accompanied by improved survival following bacterial challenge; however, the present data do not directly demonstrate the functional activity of the inferred immune mechanisms in Asian seabass.
Chatchai Rodwihok, Kim D. Thompson, Pakapon Meachasompop et al.· International Journal of Mol...· 0 citations
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