Feed restriction affects bone properties of the broiler breeder pullet femur

Feed restriction programs are used to grow broiler breeder pullets to matur ity to get better performance during the laying cycle. Femur bone propertie s were evaluated as influenced by two feed restriction programs, limited da ily access (LDA) and skip-a-day (SAD) using Arbor Acres conventional broile r breeder pullets grown to 17 wk of age using a SAD feed restriction progra m. The pullets were then assigned to two feeding programs, LDA (12 pullets) and SAD (13 pullets). The pullets were terminated at 22 wk of age, and fem ur bone properties were examined. Body weights of the two feed restricted treatments were not statistically d ifferent. The femur mineral apposition rate, an indicator of the activity o f bone-forming cells, was not different in the LDA (3.58+/-0.15 mu m/day) a nd the SAD (3.45+/-0.13 mu m/day) treatments. The number of osteons (the bo ne-forming structural unit within the femur) was also not statistically aff ected by the dietary regimes (50.5+/-4.9, LDA and 36.7+/-4.2, SAD). Bone su rface covered by osteoblasts (bone-forming cells) was significantly greater in pullets fed the LDA program. More bone-forming cells could alter final bone mass. Bone surface covered by bone-forming cells was greater near the medial and lateral areas of the femur than in the central areas, while bone surface covered by osteoclasts (cells breaking down bone) did not signific antly differ throughout the bone examined.