The prevalence and severity of laying hen keel bone fractures (KBF) is concerning to the poultry industry. There is a dearth of research on KBF during the end-of-lay. Little is known about the potentially chronic and long-term impact KBF, even when healed, may have on end-of-lay hens. To bridge this knowledge gap, studies were conducted that utilized metabolic measures such as respirometry (Chapter 2) and doubly labelled water (Chapter 3) to explore the impacts KBF have on end-of-lay hens. In both studies, the mean metabolic measurements between fractured and unfractured birds did not reveal statistically significant differences. However, intriguing findings related to the variation of results within groups, the duration of activity, and allometry suggest a potential interplay between KBF and metabolism during the end-of-lay phase. Future research is necessary to determine the exact effects KBF have on end-of-lay hens.