Secondary copper deficiency in cattle caused by molybdenum contamination of fodder: a case history.

In a herd of cattle located in central Hungary, illness and subsequent death of cows was observed. The cause of these losses was molybdenum-induced secondary copper deficiency. The origin of the environmental molybdenum was used motor oil containing molybdenum bisulfide as an additive. This split motor oil polluted the cow's pasture located on the side of a railway bed near the farm. Before the illnesses and deaths, the animals were grazing for at least 2 weeks in the contaminated area. The ill animals were recumbent and unable to rise. There was no response to treatment with 10 g calcium gluconate iv. Cows which died showed no specific lesions on necropsy. The clinical chemistry investigations showed anemia, minimal caeruloplasmin activity in the blood, and high molybdenum concentrations in the rumen contents, liver and kidney. Copper concentrations were low in liver, kidney and blood serum. The seriously ill cows died in spite of 100 mg copper glycinate injections, but the asymptomatic animals remained alive. Molybdenum pollution can cause acute clinical disease and subsequent death by interfering with copper metabolism.