| Genetic selection for economic traits in modern strains of poultry has resulted in increased demands on skeletal integrity. Laying hens are highly susceptible to bone loss, osteoporosis and fractures of bone. Bone breakage also occurs in rapidly growing broiler chickens. Strontium (Sr) has been reported to dissociate bone remodeling and have beneficial effects on bone by increasing bone formation and strength. We supplemented the diet of laying hens and young chickens with Sr to examine whether Sr would improve bone mechanical integrity and resistance to fracture.; In layers, various doses of Sr (0, 3000, 4500, and 6000 ppm) were fed to 196 thirteen week old pullets for 11 months. In broilers, the diet of 300 day-old chicks was supplemented with Sr at doses of 0, 1200, or 2400 ppm for 42 days.; Bone density and mineral content were measured by both conventional (mass/volume) and dual X-ray absorptiometry (DXA) methods. Structural and material properties were determined by three-point bending test, and micro-architectural parameters were derived from micro computerized tomography (muCT). Calcium (Ca), phosphorus (P), and Sr levels in plasma and bone as well as egg output, eggshell quality, and eggshell mineral content were also assessed.; Sr concentration in plasma and bone increased in a dose dependent manner without affecting Ca and P, although in broiler chickens treated with the higher level of Sr a significant decrease in bone Ca content was observed. Ash and Sr content of eggshells was increased as the dietary Sr level was increased. Treatment of laying hens and broiler chickens with Sr increased DXA measurements of BMD and BMC and improved bone volume and micro-architecture as measured by muCT. In laying hens, Sr improved the structural properties of the diaphyseal bone by incerseing ultimate load. In broiler chickens, dietary supplementation with Sr resulted in reduced bone stiffness but did not have any effect on ultimate bending load. Body growth, egg output and shell quality were not affected as a result of Sr.; Overall, Sr supplementation induced positive effects on bone density, volume, and micro-architecture as measured by radiographic methods. Sr treatment also improved the structural strength of diaphyseal bone in laying hens and had no positive effect on the estimated material properties of the bone tissue in laying and rapidly growing chickens. |
