To test the hypothesis that factors associated with bone strength (i.e., volumetric bone mineral density [vBMD], geometry, and microstructure) have heritable components, we exploited the 12 BXH recombinant inbred (RI) strains of mice derived from C57BL/6J (B6; low bone mass) and C3H/HeJ (C3H; high bone mass) progenitor strains. The femurs and lumbar vertebrae from each BXH RI strain were characterized for phenotypes of vBMD, microstructural, biomechanical, and geometrical properties. Methods included bending (femur) and compression (vertebra) testing, peripheral quantitative computed tomography (pQCT), and microcomputed tomography (CT). Segregation patterns of femoral and vertebral biomechanical properties among the BXH RI strains suggested polygenic regulation. Femoral biomechanical properties were strongly associated with femoral width in the anteroposterior (AP) direction and cortical thickness-geometric properties with complex genetic regulation. Vertebral vBMD and biomechanical properties measured in BXH RI strains showed a greater variability than either B6 or C3H progenitors, suggesting both progenitor strains have independent subsets of genes that yield similar vBMD and strength. The CT and pQCT data suggested that the distribution of vertebral mineral into cortical and trabecular compartments is regulated genetically. Although the B6 and C3H progenitors had similar vertebral strength, their vertebral structures were markedly different: B6 had good trabecular bone structure and modest cortical bone mineral content (BMC), whereas C3H had high cortical BMC combined with a deficiency in trabecular structure. These structural traits segregated independently in the BXH RI strains.

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A prototype enzyme linked immunoabsorbent assay (ELISA) test has been developed on the IDEXX SNAP™ device to detect antibodies to Mycobacterium avium subspecies paratuberculosis (MAP), the causative organism of Johne's disease in ruminants. Initial validation studies have been completed utilizing bovine serum as the specimen type. This SNAP test format has potential applications as an animal-side or in-clinic assay for large animal veterinarians who require a rapid test result on symptomatic or suspicious animals. Total assay time is 22 minutes. The purpose of this study was to evaluate the performance of this new MAP ELISA by testing populations of dairy cattle (n = 1276). A comparison of results obtained with the prototype SNAP assay and a USDA-licensed, microtiter-plate antibody test kit was made.