Avian Viruses that Impact Table Egg Production

SIMPLE SUMMARY: Global table egg production is a multibillion-dollar industry. Poultry eggs provide an important source of protein, and consumers demand high-quality products. The industry relies on efficiency and good management, including vaccinations against the major poultry diseases, in order to ensure that they can match consumer demand. However, although there are a number of effective disease prevention protocols in place on poultry farms, viruses that affect egg production continue to be a major constraint for the sustainability of the table egg industry globally. Various factors related to either the infecting virus, the host, or the management system have been demonstrated to contribute significantly to the challenge for effective egg production. Viral infections in laying flocks have been shown to target various biological mechanisms that are essential for the quantitative and qualitative traits of egg production. This review describes the mechanisms involved in viral diseases of poultry that induce undesirable effects on egg production. ABSTRACT: Eggs are a common source of protein and other nutrient components for people worldwide. Commercial egg-laying birds encounter several challenges during the long production cycle. An efficient egg production process requires a healthy bird with a competent reproductive system. Several viral pathogens that can impact the bird’s health or induce reversible or irreversible lesions in the female reproductive organs adversely interfere with the egg industry. The negative effects exerted by viral diseases create a temporary or permanent decrease in egg production, in addition to the production of low-quality eggs. Several factors including, but not limited to, the age of the bird, and the infecting viral strain and part of reproductive system involved contribute to the form of reproductive disease encountered. Advanced methodologies have successfully elucidated some of the virus–host interactions relevant to the hen’s reproductive performance, however, this branch needs further research. This review discusses the major avian viral infections that have been reported to adversely affect egg productivity and quality and aims to summarize the current understanding of the mechanisms that underlie the observed negative effects.