Effects of Molybdenum and Sulfate Sulfur on Metabolism of Copper in Dairy Cattle

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Abstract
First calf Holstein heifers were used to study the occurrence of molybdenum toxicity. Heifers which received diets containing from 5 to 50 ppm molybdenum and no added sulfate sulfur did not develop any of the symptoms of molybdenum toxicity such as alopecia, achromatrichia, diarrhea, emaciation, or anemia, but the levels of Cu found in the liver and blood serum were lowered. Identical results were observed in heifers which received a diet containing from 5 to 20 ppm molybdenum and 0.3% sulfate sulfur. Heifers which received 50 ppm molybdenum and 0.3% sulfate sulfur developed alopecia and achromatrichia; however, no further symptoms of molybdenum toxicity were observed. When lactating heifers were subjected to the stress of being housed in a pole barn and fed in an open lot during winter months, there was no increase in susceptibility to molybdenum toxicity observed. Four heifers which received a diet containing either 100 or 200 ppm molybdenum with 0.3% sulfate sulfur became emaciated, developed alopecia, achromatrichia, and lost nervous control of their hind quarters within 3 weeks; however, no changes were observed in liver Cu or blood serum copper levels. Copper added to the diet of heifers which developed achromatrichia and alopecia completely corrected these conditions.