Molybdenum requirement of female rats

Sixty 3-wk-old female Sprague-Dawley rats were randomly divided into six groups of 10 animals each. Group 1 was fed for 8 wk purified AIN-76A diet (basal diet) containing 0.025 mg molybdenum/kg diet. Groups 2-6 were fed the same basal diet supplemented with sodium molybdate to provide total dietary Mo of 0.050, 0.100, 0.200, 0.400 and 0.800 mg/kg diet, respectively. Molybdenum concentration in liver and brain increased linearly up to the 0.200 mg Mo/kg diet level. Beyond this level, no further significant increase occurred. Dietary Mo of 0.100 mg/kg elevated the Mo concentration in heart to its maximal level. Supplementation with 0.025 mg Mo/kg to a total of 0.05 mg Mo/kg diet significantly increased Mo concentration in spleen and kidney; higher levels of dietary Mo did not result in further significant responses. Molybdenum supplementation significantly increased the activities of xanthine dehydrogenase/oxidase (XDH), sulfite oxidase and superoxide dismutase in the liver, and of XDH in small intestinal mucosa. Maximal activities were attained at 0.050, 0.050, 0.200 and 0.100 mg Mo/kg diet, respectively. Dietary Mo of 0.200 mg/kg diet was estimated as the Mo requirement of rats fed the AIN-76A diet.