RESUMO
Poultry enterprise is challenged with high economic losses due to viral infections. The outbreak of such infections, including Newcastle disease, avian influenza, infectious bronchitis and infectious bursal disease, could undermine poultry performance leading to decreased meat and egg production. The potency of vaccines in recent times has dropped with the rise in the virulence of antigens, which can interrupt vaccination defence. Natural herbs and phytochemicals have been extensively recommended because of their vast advantageous effects. Garlic and its bioactive organo-sulphur compounds have been proven to have antiviral, immunomodulatory and other pharmaceutical properties. Remarkable effects in poultry include a decrease in viral loads, an increase in antibody titres, lessening inflammatory cytokines and augmenting antiviral gene expression; however, methods of preparation, the dose of bioactive compounds and proportions administered may cause disparities in different reports. Therefore, this review highlights the potential of garlic against viral diseases, immunomodulatory, toxicity and pathological status in embryonated chicken eggs and poultry.