article · BMC Veterinary Research
Supplementing Nile tilapia diets with the marine microalga Nannochloropsis oculata enhances fish growth performance and nutritional quality. In a seven-week study, fish were fed either a basal control diet or diets containing five or ten percent microalgae. Both supplemented groups showed improvements in growth indices, whole-body crude protein, and favourable shifts in lipid profiles, notably higher levels of high-density lipoproteins, lower low-density lipoproteins, and increased omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid. Additionally, the microalga stimulated the expression of key immune and antioxidant-related genes, including heat-shock protein 70, glutathione-S-transferase, and interleukin-1 beta, while interleukin-10 increased in the ten percent group. Tissue analysis of the intestine, liver, and spleen confirmed that dietary inclusion was safe, supporting this microalga as a viable nutraceutical supplement for sustainable aquaculture production.
Aquaculture requires sustainable feed ingredients that can improve fish welfare and dietary value without harming fish biology. Demonstrating that Nannochloropsis oculata boosts growth, elevates health-promoting omega-3 fatty acids, and stimulates natural immune defences provides a functional feeding strategy for farmed tilapia. This approach supports sustainable fish farming by offering a safe, nutrient-rich supplement that benefits both fish health and consumer nutritional quality.
This work directly targets the aquafeed manufacturing sector, specifically producers formulating functional diets for Nile tilapia. By showing proven benefits at inclusion rates of five and ten percent, the research provides clear inclusion benchmarks. The study sits at an applied testing stage in a controlled feeding trial, meaning further pilot-scale production tests and economic cost-benefit assessments are likely required before widespread commercial feed integration.
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Nannochloropsis oculata (N. oculata) is a marine microalga containing bioactive compounds and a high omega-3 polyunsaturated fatty acid (ω-3 PUFAs). Therefore, it is very promising for nutraceutical and the functional food industry applications. Three groups of Nile tilapia (forty-five fish/group) were fed on basal diets or diets containing 5% (N5) or 10% (N10) of the microalga N. oculata for seven weeks. Fish growth performance, proximate composition, and lipid (fatty acids/ FAs and lipoproteins) profile were estimated. In addition, the expression pattern of some lipid metabolism and immune-relevant genes were assessed. An enhancement in whole body crude protein and growth indices of Nile tilapia was observed on both the supplemented groups N5 and N10. Higher levels of high-density lipoproteins (HDL); and lower levels of the low-density lipoproteins (LDL) were evident in both supplemented groups, while the cholesterol and triglycerides (TG) levels were similar among groups. Ω-3 PUFAs were the significant FAs profile of tilapia fed on N. oculata-supplemented diets in terms of eicosapentaenoic acid, docosahexaenoic acid, and n3/n6 ratio. Concerning the gene expression pattern, heat-shock protein70, glutathione-S-transferase, glutathione peroxidase, and interleukin-1β (IL-1β) were elevated significantly in both supplemented groups. IL-10 is only upregulated in the N10 group. The lipid metabolism-related gene expression showed downregulation of only fatty acid synthase (FAS) in both supplemented groups, with no statistical changes in Peroxisome proliferator-activated receptor alpha (PPARα). Tumor necrosis factor-α (TNF-α), Transforming growth factor-β1 (TGF-β1), and the apoptotic related genes [caspase3 and Proliferating cell nuclear antigen (PCNA)] showed insignificant changes among groups. The histopathological examination of the intestine, liver, and spleen supports our findings and confirms the benefits and safeness of N. oculata dietary inclusion. Collectively, N. oculata is a very promising nutraceutical for improving fish health and sustainability of aquaculture production.
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DOI: 10.1186/s12917-023-03618-z
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