Assessing bone mineral density in vivo: dual energy X-ray absorptiometry

Abstract

Dual-energy X-ray absorptiometry can be used as a noninvasive tool to monitor the skeletal integrity of live birds. A pDexa X-ray bone densitometer was used to determine bone mineral densities (BMD) of the left tibia together with the fibula and the humerus of live, unanesthetized birds. Densitometry effectively detected changes in bone integrity of live birds fed varying levels of dietary calcium. Hens consuming 1.8, 3.6, or 5.4% dietary calcium had BMD of 0.147, 0.157, and 0.176 g/cm2 (SEM = 0.005), respectively (linear effect, P < 0.001). Likewise, bone ash weight, breaking force, stress, modulus of elasticity, and eggshell traits also increased linearly in response to increased calcium in the diet (P < 0.05). Densitometric live scans for BMD were positively correlated (P < 0.001) with bone breaking force (r = 0.65) and bone ash (r = 0.77). We also monitored BMD in live Leghorn and broiler females during their life cycle. The tibial BMD of White Leghorns and broilers increased from 15 to 65 wk of age with the BMD of the broiler tibia increasing at a greater rate than that of the Leghorn tibia (line x age interaction, P < 0.0001). A precipitous drop in BMD occurred during an induced molt of Leghorns subjected to 10 d of feed withdrawal. Our long-term goal is to improve skeletal integrity in egg-type chickens by genetic selection for improved BMD. By crossing a broiler with an egg-laying line, an F2 resource population of birds has been developed to identify quantitative trait loci influencing BMD in chickens.

Gestational high saturated fat diet alters C57BL/6 mouse perinatal skeletal formation

“…A complete evaluation of bone to assess relative risk of fragility and future development of osteoporosis now includes detailed observation of trabecular bone phenotype, including trabecular number, diameter, spacing, connectivity, and anisotropy. Increased spacing, and decreased number, diameter, connectivity, and anisotropy signal inferior architectural soundness, and elevate long-term risk of bone fragility and osteoporosis (Hester et al, 2004;Schreiweis et al, 2003). Other traditional gross morphometric techniques, such as potassium hydroxide tissue clearing and Alizarin Red staining of mineralized bone are also appropriate for crude determination of skeletal structures and lengths.…”

Performance, Livability, and Carcass Yield of Slow- and Fast-Growing Chicken Genotypes Fed Low-Nutrient or Standard Diets and Raised Indoors or with Outdoor Access

“…The left wing and drumstick were collected from an average of 2 birds per replicate pen per treatment, resulting in a sample size of 6 to 11 observations per treatment. Samples were frozen and express-mailed in dry ice to Purdue University, where they were thawed and scanned with muscle and skin intact using dual-energy x-ray absorptiometry for determination of bone mineral density (BMD; Hester et al, 2004).…”

The effect of feeder space allocation on productivity and physiology of Hy-Line W-36 hens housed in conventional cages

“…The humerus, which comprises cancellous, cortical, and, in some cases, med-ullary bone (Fleming et al, 1998), was chosen for scanning because it is representative of the structural bones usually affected by osteoporosis and is one of the most frequently fractured bones in caged hens (Gregory and Wilkins, 1989). For comparison, the tibia, containing medullary bone, was scanned (Hester et al, 2004). The live, unanesthetized hens were restrained on their backs in a foam holding device and secured with fastening straps (Schreiweis et al, 2003;Hester et al, 2004).…”