Molybdenum cattle poisoning

Symptoms of molybdenum poisoning in cattle include emaciation, diarrhea, anemia, stiffness, and fading of hair color. Vegetation containing 230 mg/kg of this substance affects cattle. 

In terrestrial vegetation, molybdenum and sulfur interfere with copper-induced deficiencies (Gupta 1979). Copper poisoning in cattle and other ruminants is governed by dietary concentrations of molybdenum and sulfate (Lewis et al. 1967 Todd 1969 Buckley and Tait 1981 Eisler 1989). Molybdenum and sulfur in mammalian diets cause a decrease in the availability of copper because of the formation of the biologically unavailable copper-thiomolybdate complex (Aaseth and Norseth 1986). Cattle die when grazing for extended periods on pastures where the ratio of copper to molybdenum... 

Parada, R. 1981. Zinc deficiency in molybdenum poisoned cattle. Vet. Human Toxicol. 23 16-21. 

Sheep are more susceptible to copper poisoning than are cattle, but cattle are more sensitive to molybdenum poisoning than are sheep. The in vivo relationship between copper and molybdenum is well understood. Excess copper induces molybdenum deficiency and vice versa. The most frequent cause of copper poisoning in sheep is by uninformed farmers feeding cattle feed to sheep. Copper from different sources is additive. Copper is an essential element for cattle and is usually added to their feeds however, molybdenum is not considered essential and is therefore not added. Cattle feeds therefore have high copper concentrations and no molybdenum feeding this ration to sheep upsets the normal 6 1 copper molyb-denum ratio in vivo. 

Horses are generally considered to be tolerant of dietary copper deficiencies and of copper and molybdenum excesses that affected mminants. Yet molybdenum accumulated in equine liver and has been implicated as a possible contributory factor in bone disorders in foals and yearlings grazing pastures containing 5.0-25.0 mg Mo/kg. Cattle and horses are highly susceptible to pyrrolizidine alkaloids, an ingredient in certain poisonous plants such... 

Domestic mminants, especially cattle, are especially sensitive to molybdenum poisoning when copper and inorganic sulfate are deficient. Cattle are adversely affected - and die if not removed - when grazing on pastures where the ratio of copper to molybdenum is <3, or if they are fed low copper diets containing molybdenum at 2.0-20.0 mg/kg diet death usually occurs when tissue residues exceed 10.0 mg Mo/kg body weight. The resistance of other species of mammals tested, including domestic livestock, small laboratory animals, and wildlife, was at least tenfold higher than that of cattle. Mule deer (Odocoileus hemionus), for example, showed no adverse effects at dietary levels of 1000.0 mg/kg. 

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