To test this hypothesis , we used ovariectomized rats as a model of postmenopausal osteoporosis to examine the deleterious effects of Cd on bone with and without added P. Fifty 3-month-old ovariectomized Sprague-Dawley rats were assigned to five treatment groups ( n = 10 per group ) for 3 months as follows : ( 1 ) control ; ( 2 ) 50 ppm Cd ; ( 3 ) 50 ppm Cd plus 1.2 % P ; ( 4 ) 200 ppm Cd ; and ( 5 ) 200 ppm Cd plus 1.2 % P.