Feed Restriction Affects Bone Properties of the Broiler Breeder Pullet Femur

Abstract

Feed restriction programs are used to grow broiler breeder pullets to maturity to get better performance during the laying cycle. Femur bone properties were evaluated as influenced by two feed restriction programs, limited daily access (LDA) and skip-a-day (SAD) using Arbor Acres conventional broiler breeder pullets grown to 17 wk of age using a SAD feed restriction program. 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 femur bone properties were examined.Body weights of the two feed restricted treatments were not statistically different. The femur mineral apposition rate, an indicator of the activity of bone-forming cells, was not different in the LDA (3.58±0.15 μm/day) and the SAD (3.45±0.13 μm/day) treatments. The number of osteons (the bone-forming structural unit within the femur) was also not statistically affected by the dietary regimes (50.5±4.9, LDA and 36.7±4.2, SAD). Bone surface 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 (cell breaking down bone) did not significantly differ throughout the bone examined.