AN AVIAN MODELING APPROACH FOR ANALYZING BONE LOSS DUE TO DISUSE

Osteopenia has been a major skeletal problem of leghorns in production . Mechanical usage has been considered a major factor in controlling u ltimate bone mass. A disuse model was characterized over a 35 day peri od in pullets to determine the sequential temporal change in lamellar cortical bone of the wing. Ulna cortical bone area was decreased at al l four time intervals in the immobilized wings. At 21 days post-immobi lization, the cortical bone area was decreased most significantly Oste oblastic activity was most consistently altered by immobilization on t he posterior quadrant of the ulna. Cortical endosteal eroded surface w as significantly increased on day 14 in experiment 1 and day 28 in exp eriment 2. Nondestructive material testing indicated that a 30% to 40% reduction in stiffness for the immobilized wing.