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Abstract
The impacts of vitamin D3 on bone metabolism are complex. Additionally, the application of vitamin D3 metabolites, like 25-hydroxyvitamin D3 on laying hens has shown several effects on egg production and bone quality throughout research. Limited research has focused on the long-term supplementation of 25-hydroxyvitamin D3 from rearing continuing through the laying period. Research can show the qualities of laying hen bone make up and its appealing research model to understand further laying hen bone physiology as well as to develop a new strategy to alleviate osteoporosis, deformities, and fractures. In the current studies, essential oils and vitamin D3 had potential improvements in bone physiology, structure and growth during the rearing period that provides a long-term positive effect throughout the laying period on overall production and maintenance. In the first study, 1,25-hydroxyvitamin D3 with and without the addition of higher calcium and phosphorus, were added to pullet diets to understand its role in femur development and overall structure. The results indicated the role of 1,25-hydroxyvitamin D3 supplementation to pullets improved bone growth and the treatments with the addition of higher calcium and phosphorus improved cortical bone structure by increasing mineral deposition. In continuation of the rearing study, the study progressed through the laying period. The effects continued to maintain bone structure for the 1,25-hydroxyvitamin D3 with higher calcium and phosphorus along with higher body weight and egg production. In the next study, essential oils (fish and flaxseed) and 1,25-hydroxyvitamin D3 was utilized during the rearing and laying periods investigate the effects on the keel bone properties. Results indicated a positive impact of keel bone development and calcium and phosphorus absorption for birds fed the essential oils and 1,25-hydroxyvitamin D3 treatments. Lastly, an osteogenic study was conducted on keel bone development and structural growth to observe the anatomy and physiology of the keel bone using the latest state-of-the-art technologies. The study revealed promising strategies for the rearing and laying periods to improve keel bone health and overall management.