Criteria to evaluate bone mineralization in cattle: II. Noninvasive techniques.

An experiment was conducted to evaluate the capabilities of dual photon absorptiometry (PA), radiographic photometry (RP), and ultrasound (U) to estimate bone mineral content (BMC) and bone strength of a group of bovine third metacarpals (McIII). Metacarpals were chosen for evaluating BMC and bone strength because of their accessibility and susceptibility to biomechanical stress. The right and left McIII of 14 Angus heifers (24 to 32 mo of age) were collected at slaughter and all soft tissues (including periosteum) were removed. The BMC was estimated at both the midpoint and 3 cm proximal to the midpoint on the McIII diaphysis. Metacarpals then were tested by three-point bending to determine breaking load (BL) and breaking strength (BS). Bones were reassembled and two 2-cm sections were removed, one at the midpoint and one 1 cm proximal to the midpoint section. Sections then were ashed and ash content was expressed as grams per 2-cm slice and defined as BMC. Correlation coefficients (r) between BMC vs PA, RP, and U were .908 (P less than .0001), .967 (P less than .0001), and .565 (P less than .0001), respectively; r values between BS vs PA, RP, and U were .406 (P less than .05), .429 (P less than .05), and .499 (P less than .01), respectively, and r values between BL vs PA, RP, and U were .870 (P less than .0001), .865 (P less than .0001), and .588 (P less than .001), respectively. These data indicate that noninvasive techniques are useful in predicting BMC and BL in the bovine.