Clomiphene citrate, a mixed estrogen agonist-antagonist, protects mature ovariectomized breeder rats from changes in total body calcium and from deterioration of femur structure. Over 6 months, mature ovariectomized rats took up calcium at the rate of 0.7 +/- 0.5 mg/day, while normal controls gained 2.5 +/- 0.7 mg/day (mean +/- SEM) as measured by whole body neutron activation analysis. Injections of clomiphene (20 mg/kg/week) kept ovariectomized rats in positive calcium balance at 2.0 +/- 0.5 mg/day. Reductions in total femur calcium content, cortical thickness, and visible trabeculae of femurs in ovariectomized animals were prevented by chronic clomiphene administration. These results in animals suggest a possible new line of investigation of the use of antiestrogenic drugs as therapeutic agents for hormone-dependent osteoporosis in animals and humans.
Variations in hatching time and their subsequent effect on placement weight, chick mortality, and four-week body weight were evaluated. Hatching intervals for three experiments ranged from 32 hr to 60 hr with total incubation time ranging from 20.67 to 21.75 days. Early hatched chicks showed a significant reduction in placement weight which continued to be evident at four weeks of age. The delayed placement resulting from early hatch also increased mortality during the first week of brooding as did holding chicks in boxes in excess of 30 hr.
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