Supplemental Microalgal DHA and Astaxanthin Affect Astaxanthin Metabolism and Redox Status of Juvenile Rainbow Trout

Nutritional and immunological evaluation of Nannochloropsis oculata as a potential Nile tilapia-aquafeed supplement

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.

Impacts of Fortifying Nile Tilapia (Oreochromis niloticus) Diet with Different Strains of Microalgae on Its Performance, Fillet Quality and Disease Resistance to Aeromonas hydrophila Considering the Interplay between Antioxidant and Inflammatory Response

The oxidative stress facing fish during intensive production brings about diseases and mortalities that negatively influence their performance. Along with that, the increased awareness of omega-3 polyunsaturated fatty acids (omega-3-PUFAs) health benefits has been triggered the introduction of alternative additives in aqua feed that cause not only modulation in fish immune response but also fortification of their fillet. In this context, the role of microalgae mix (NSS) containing Nannochloropsis oculate and Schizochytrium and Spirulina species, which were enriched with bioactive molecules, especially EPA and DHA, was assessed on Nile tilapia's performance, fillet antioxidant stability, immune response, and disease resistance. Varying levels of NSS (0.75, 1.5, and 3%) were added to Nile tilapia's diet for 12 weeks and then a challenge of fish with virulent Aeromonas hydrophila (A. hydrophila) was carried out. Results showed that groups fed NSS, especially at higher levels, showed an improved WG and FCR, which corresponded with enhanced digestive enzymes' activities. Higher T-AOC was detected in muscle tissues of NSS3.0% fed fish with remarkable reduction in ROS, H2O2, and MDA contents, which came in parallel with upregulation of GSH-Px, CAT, and SOD genes. Notably, the contents of EPA and DHA in fillet were significantly increased with increasing the NSS levels. The mean log10 counts of pathogenic Vibrio and Staphylococcus species were reduced, and conversely, the populations of beneficial Lactobacillus and Bacillus species were increased more eminent after supplementation of NSS3.0% and NSS1.5%. Moreover, regulation of the immune response (lysozyme, IgM, ACH50, NO, and MPO), upregulation of IL-10, TGF-β, and IgM, and downregulation of IL-1β, TNF-α, HSP70,and COX-2 were observed following dietary higher NSS levels. After challenge, reduction in A. hydrophila counts was more prominent, especially in NSS3.0% supplemented group. Taken together, the current study encourages the incorporation of such microalgae mix in Nile tilapia's diet for targeting maximum performance, superior fillet quality, and protection against A. hydrophila.

Antioxidant Defences and Redox Homeostasis in Animals

For many years reactive oxygen species (ROS) production in biological systems has been considered to be detrimental [...]