Molybdenum ruminants

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... 

The element molybdenum (Mo) is found in all living organisms and is considered to be an essential or beneficial micronutrient. However, molybdenum poisoning of ruminants has been reported in at least 15 states and 8 foreign countries. Molybdenum is used primarily in the manufacture of steel alloys. Its residues tend to be elevated in plants and soils near molybdenum mining and reclamation sites, fossil-fuel power plants, and molybdenum disposal areas. Concentrations of molybdenum are usually lower in fish and wildlife than in terrestrial macrophytes. 

Ivan, M. and D.M. Veira. 1985. Effects of copper sulfate supplement on growth, tissue concentration, and ruminal solubilities of molybdenum and copper in sheep fed low and high molybdenum diets. Jour. Dairy Sci. 68 891-896. 

Todd, J.R. 1976. Problems of copper-molybdenum imbalance in the nutrition of ruminants in northern Ireland. Pages 33-49 in W.R. Chappell and K.K. Peterson (eds.). Molybdenum in the Environment. Vol. 1. The Biology of Molybdenum. Marcel Dekker, New York. 

Ward, G.M. 1978. Molybdenum toxicity and hypocuprosis in ruminants a review. Jour.Anim. Sci. 46 1078-1085. 

Copper absorption is depressed by ascorbic acid, dietary phytuies. cadmium, mercury, silver, and zinc. It appears that metals impede copper absorption through competition lor meml-hinding sites. Dietary copper, molybdenum, amt sulfur arc closely interrelated in optimum copper und molybdenum nutrition of ruminants. Increase pasture molybdenum content and low-pasture copper result in a condition known as "peat scours. ... 

The determination of molybdenum in soil is of interest because molybdenum is necessary for normal crop growth, but an excess in forage has a toxic effect on ruminants. The absorption of molybdenum by plants is influenced by other soil components, especially extractable iron, pH and organic matter. The average abundance of molybdenum in soils is about 2 ppm, but deficient soils can have much less than 1 ppm [171]. Jiao et al. [172] and Rowbottom [173] have reviewed methods for the determination of molybdenum in soils. 

Molybdate is known to induce copper deficiency, ft was found that the administration of molybdenum compounds, particularly with added sulfate, impaired copper metabolism in ruminants. Tetrathiomolybdate has been used to treat patients who were intolerant to D-penicillanune, trientine, and zinc. Tetrathiomolybdate seems to act both by blocking the intestinal absorption of copper and keeping it in a metabolically inert chelated form, which is not taken up by the liver. However, it induces only a modest cupriuresis. There are also known toxic effects of tetrathiomolybdate on the skeletal system of growing animals. Thus one should be extremely careful in administering this compound. It should be considered as an experimental drug. 

Molybdenum is important in agriculture, and plays a vital part in the fixation of atmospheric nitrogen. However, the concentration present in the soil is critical in relation to copper metabolism. If the molybdenum intake by animals is too high, especially with ruminants, then a copper-deficiency problem called "molybdenosis" can occur. On the other hand, too low an intake of molybdenum can lead to excessive copper metabolism and copper poisoning. The total use of molybdenum... 

The addition of molybdenum to the diet of ruminants deficient in copper worsens this deficiency by enhancing biliary excretion of copper, when this is not a major copper... 

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