Recently, the use of essential oils (EOs) or their bioactive compounds encapsulated by nanoparticles as alternative supplements for in-feed antimicrobials is gaining attention, especially in organic poultry production. Focusing on eugenol, its incorporation into the nanoformulation is a novel strategy to improve its stability and bioavailability and thus augment its growth-boosting and antimicrobial activities. Therefore, we explored eugenol nanoemulsion activities in modulating growth, digestive and gut barrier functions, immunity, cecal microbiota, and broilers response to avian pathogenic E. coli challenge (APEC) O78. A total of 1,000 one-day-old broiler chicks were allocated into five groups; negative control (NC, fed basal diet), positive control (PC), and 100, 250, and 400 mg/kg eugenol nanoemulsion supplemented groups. All groups except NC were challenged with APEC O78 at 14 days of age. The results showed that birds fed eugenol nanoemulsion displayed higher BWG, FI, and survivability and most improved FCR over the whole rearing period. Birds fed 400 mg/kg of eugenol nanoemulsion sustained a higher growth rate (24% vs. PC) after infection. Likely, the expression of digestive enzymes' genes (AMY2A, CCK, CELA1, and PNLIP) was more prominently upregulated and unaffected by APEC O78 challenge in the group fed eugenol nanoemulsion at the level of 400 mg/kg. Enhanced gut barrier integrity was sustained post-challenge in the group supplemented with higher levels of eugenol nanoemulsion as evidenced by the overexpression of cathelicidins-2, β-defensin-1, MUC-2, JAM-2, occludin, CLDN-1, and FABP-2 genes. A distinct modulatory effect of dietary eugenol nanoemulsion was observed on cytokine genes (IL-1β, TNF-α, IL-6, IL-8, and IL-10) expression with a prominent reduction in the excessive inflammatory reactions post-challenge. Supplementing eugenol nanoemulsion increased the relative cecal abundance of Lactobacillus species and reduced Enterobacteriaceae and Bacteriods counts. Notably, a prominent reduction in APEC O78 loads with downregulation of papC, iroN, iutA, and iss virulence genes and detrimental modifications in E. coli morphological features were noticed in the 400 mg/kg eugenol nanoemulsion group at the 3rd-week post-challenge. Collectively, we recommend the use of eugenol nanoemulsion as a prospective targeted delivery approach for achieving maximum broilers growth and protection against APEC O78 infection.

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.

The present study was carried out to investigate the efficacy of propolis and norfloxacin against Aeromonas hydrophila in Nile catfish (Clarias garipeinus). Fish were collected from a private fish farm in Sharkia Governorate and fed commercial fish diet. Fish were divided into six groups; Group 1: non-infected non-treated, Group 2: experimentally infected with A. hydrophila and non-treated, Group 3: normal fish administered propolis in feed by dose (10g/kg BW for 10 days), Group 4: infected fish treated with therapeutic dose of norfloxacin (10mg/kg BW for 10 days), Group 5: infected fish treated with propolis and Group 6: infected fish treated with therapeutic dose of norfloxacin and propolis (with the previous dose). The results indicated that propolis and norfloxacin were effective against A. hydrophila. The hematological parameters were improved in Groups 4, 5 and 6 when compared with Group 2. The second group showed a significant increase (p<0.05) in serum aspartate aminotransferase (AST), alanine aminotransferrase (ALT), urea, creatinine and malondialdhyde activity, while the mentioned parameters were improved decreased in Groups 5 and 6. Also, our results revealed a significant increase (p<0.05) in immunological parameters in Groups 3, 5 and 6. Moreover, this study also reported the pathological lesions in gills, liver, kidneys, heart, spleen and intestine of fish infected with A. hydrophila which became milder in treated fish especially with propolis and antibiotic. The present results suggest that the administration of propolis and norfloxacin were effective against A. hydrophila without hazard effects on hematological and biochemical parameters.

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