Excess of Molybdenum in Herbage as a Possible Contributory Factor in Equine Osteodystrophia

DEFECTS in nutrition which predispose to osteodystrophic conditions in the horse include a dietary deficiency of phosphorus1 or disturbance in the vitamin D – calcium – phosphorus relationship. With regard to the influence of trace minerals, Davis2 found that the presence of small amounts of molybdenum, ranging from 2 to 25 p.p.m. in young growing herbage, was associated with defective bone metabolism in herbivora, consequent on the effects of molybdenum on the utilization of both phosphorus and copper. More recently, Arrington and Davis3 in limited phosphorus metabolism studies with rabbits reported that molybdenum decreased phosphorus absorption while at the same time increasing the excretion of phosphorus.