Molybdenum toxicity in sheep: Epiphysiolysis,exotoses and biochemical changes

Fifteen sheep were allowed to graze pasture that had been sprayed three times with molybdenum at the rate of 420 g per hectare. Shortly after lameness was observed in 2 of the sheep, all were killed and necropsied. In 8 animals there were exostoses and haemorrhages about the long-bones, and in 2 other sheep the great trochanters of the femurs were loosened. The lesions appeared to be due to defects in the connective tissue at points where muscle is inserted into bone and to defects in the epiphysial plates of the trochanters. No similar lesions were found in 15 control sheep grazing unsprayed pasture. During the course of the experiment the molybdenum concentration of the plasma of the experimental sheep increased above that of control sheep. Experimental sheep had a greater proportion of plasma copper that was insoluble in trichloroacetic acid than control sheep. Amounts of copper in the liver of experimental animals were reduced, but copper in the periosteum was increased compared with controls.