Molybdenum Poisoning of Cattle in the Swan River Valley of Manitoba1

Molybdenum poisoning of cattle caused by high concentrations of molybdenum in the forage has been found to exist in the Swan River Valley of Manitoba. Typical symptoms include severe diarrhoea, emaciation, anaemia, fading of hair colour, excessive craving for salt, and often death Toxic herbage contained up to 25 6 p p m. of molybdenum while pasture samples from the Brandon and Winnipeg areas contained less than 1 9 p.p.m. The toxicity was overcome by the daily administration of 2 grams of copper sulphate as either a drench or salt lick. The disease was also produced experimentally in cattle by drenching with ammonium molybdate, but considerably more elemental molybdenum than found in toxic forage was required to induce the disorder in barn-fed cattle. Evidence was also obtained to show that the toxicity may pass through into the milk and affect the calf, but that cattle soon develop a resistance to the passage of ingested molybdenum into the milk