Eggshell apex abnormality: the silent threat to egg quality in layer chickens

Eggshell apex abnormality (EAA) is an important but often overlooked eggshell defect that can silently affect egg quality, breakage, marketability, and profitability in commercial layer production. Unlike obvious cracked, thin, or misshapen eggs, EAA may remain unnoticed during routine inspection until the affected egg is examined under strong light. The abnormality typically appears at the pointed end of the egg as localised roughness, increased translucency, thinning, and structural weakness, making affected eggs more susceptible to breakage and downgrading. EAA is not simply a calcium-deficiency problem; it reflects the interaction of several factors, including nutrition, heat stress, flock age, reproductive physiology, and infectious diseases. Among infectious factors, Mycoplasma synoviae (MS) is consistently associated with EAA, while prior exposure to infectious bronchitis virus may further increase its occurrence. Structural investigations have demonstrated marked alterations in the shell architecture of affected eggs, explaining their reduced mechanical strength. The condition is particularly relevant to intensive layer production systems, where prolonged laying cycles, high environmental temperatures, and infectious challenges can collectively compromise shell quality. Early recognition through visual examination and candling, combined with flock-level assessment and appropriate laboratory testing when MS is suspected, can help identify the underlying cause. Effective management requires a cause-directed approach that combines balanced calcium–phosphorus nutrition with adequate vitamin D₃, heat-stress reduction, strengthened biosecurity, appropriate vaccination, responsible antimicrobial use, and continuous flock surveillance. Greater awareness of EAA among poultry producers and veterinarians can help reduce abnormal and downgraded eggs, minimise avoidable economic losses, and protect the profitability of modern layer farming. The central message is simple: when an egg looks normal at first glance, it may still be telling you that something is wrong inside the flock.