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Eimeria tenella and Eimeria bovis are complex parasites responsible for the condition of coccidiosis, that invade the animal gastrointestinal intestinal mucosa causing severe diarrhoea, loss of appetite or abortions, with devastating impacts on the farming industry. The negative impacts of these parasitic infections are enhanced by their role in promoting the colonisation of the gut by common foodborne pathogens. The aim of this study was to test the anti-Eimeria efficacy of maltodextrin, sodium chloride, citric acid, sodium citrate, silica, malic acid, citrus extract, and olive extract individually, in vitro and in combination, in vivo. Firstly, in vitro infection models demonstrated that antimicrobials reduced (p < 0.05), both singly and in combination (AG), the ability of E. tenella and E. bovis to infect MDBK and CLEC-213 epithelial cells, and the virulence reduction was similar to that of the anti-coccidial drug Robenidine. Secondly, using an in vivo broiler infection model, we demonstrated that AG reduced (p = 0.001) E. tenella levels in the caeca and excreted faeces, reduced inflammatory oxidative stress, improved the immune response through reduced ROS, increased Mn-SOD and SCFA levels. Levels of IgA and IgM were significantly increased in caecal tissues of broilers that received 0.5% AG and were associated with improved (p < 0.0001) tissue lesion scores. A prophylactic approach increased the anti-parasitic effect in vivo, and results indicated that administration from day 0, 5 and 10 post-hatch reduced tissue lesion scores (p < 0.0001) and parasite excretion levels (p = 0.002). Conclusively, our in vitro and in vivo results demonstrate that the natural antimicrobial mixture (AG) reduced parasitic infections through mechanisms that reduced pathogen virulence and attenuated host inflammatory events., (© 2021. The Author(s).)

The aim of this study was to test in vitro the ability of a mixture of citrus extract, maltodextrin, sodium chloride, lactic acid and citric acid (AuraShield L) to inhibit the virulence of infectious bronchitis, Newcastle disease, avian influenza, porcine reproductive and respiratory syndrome (PRRS) and bovine coronavirus viruses. Secondly, in vivo, we have investigated its efficacy against infectious bronchitis using a broiler infection model. In vitro, these antimicrobials had expressed antiviral activity against all five viruses through all phases of the infection process of the host cells. In vivo, the antimicrobial mixture reduced the virus load in the tracheal and lung tissue and significantly reduced the clinical signs of infection and the mortality rate in the experimental group E2 receiving AuraShield L. All these effects were accompanied by a significant reduction in the levels of pro-inflammatory cytokines and an increase in IgA levels and short chain fatty acids (SCFAs) in both trachea and lungs. Our study demonstrated that mixtures of natural antimicrobials, such AuraShield L, can prevent in vitro viral infection of cell cultures. Secondly, in vivo, the efficiency of vaccination was improved by preventing secondary viral infections through a mechanism involving significant increases in SCFA production and increased IgA levels. As a consequence the clinical signs of secondary infections were significantly reduced resulting in recovered production performance and lower mortality rates in the experimental group E2.