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Recent Developments in Cobalt and Copper in Ruminant Nutrition: A Review¹

Department of Animal Science, University of Florida, Gainesville 32601

ABSTRACT

Cobalt and copper have been recognized as dietary essentials for ruminants since the 1930's, and deficiencies of both minerals have occurred under natural grazing conditions in many countries of the world. Deficiencies are infrequent with drylot feeding, particularly if grains serve as a portion of the diet. Cobalt in the form of vitamin B₁₂ is interrelated with iron and copper in hematopoiesis and, thus, indirectly involved with molybdenum. Vitamin B₁₂ may function in the formation of excretion products of selenium and thereby reduce the animal's susceptibility to selenium toxicity. Copper metabolism is influenced by many dietary factors, some of which include sulfate sulfur, molybdenum, zinc, protein level, and protein source. Because of the many factors influencing copper metabolism, it is difficult to determine precise dietary copper requirements and to predict potentially toxic levels of copper for ruminants under different feeding programs. Cobalt is comparatively less toxic than copper. Sheep and young cattle are more susceptible to copper toxicity than are mature cattle and may suffer from poisoning even when dietary copper levels are considered to be in the normal range. Several forms of supplemental cobalt and copper are effective in assuring adequate dietary intakes under deficient conditions.

¹ Presented at the Sixty-fourth Annual Meeting of the American Dairy Science Association, University of Minnesota, Minneapolis, June 25, 1969.