Optimizing eggshell quality in extended laying periods: Insights and strategies

Extending the laying period in hens offers substantial financial and environmental benefits. However, maintaining stable egg quality, particularly eggshell quality, remains a significant challenge. This review summarizes the age-related changes in eggshell quality and, based on these changes, discusses potential strategies to help maintain eggshell quality during the extended laying period. Recent studies tracking the age-related changes in eggshell quality have highlighted the phased and complex nature of these alterations, with multifaceted modifications in the eggshell's multilayered structure and composition. These changes are primarily driven by physiological declines in key organs, such as the oviduct, skeleton, and intestines. To address these challenges, several effective strategies have been taken or proposed. These include optimizing dietary calcium levels and limestone particle size, as well as employing sequential feeding strategies to ensure adequate and timely calcium provision for eggshell formation. Additionally, supplementing with vitamin D₃ and its metabolites, flavonoids, and probiotics can enhance calcium absorption and transport within laying hens. Increasing the skeletal calcium reservoir also contributes to the alleviation of pressure on calcium demand during long-term laying. Furthermore, interventions aimed at remodeling the eggshell matrix, such as the use of trace elements, organic acids, plant extracts, and maintaining an optimal dietary electrolyte balance, provide promising solutions for improving the ultrastructure and integrity of eggshells. These strategies should be implemented throughout the laying cycle, with particular emphasis on early interventions during critical phases of eggshell deterioration. Overall, recent achievements in nutritional strategies hold promise for successfully extending laying cycles.