SUMMARYSevere clinical copper deficiency has been recognized for some years on a number of farms within an area of 10 square miles in North Staffordshire. Response to injected copper is good and supplementation is now regular practice. One of the causes would appear to be a dietary excess of molybdenum, confirmed in soil and pasture.Geochemical reconnaissance in 1965 delineated areas totalling 60 square miles, including the above area, in which molybdenum occurs in above normal concentrations in stream sediments, rocks, soils and pasture. The source of the molybdenum was found to be black marine shales of Carboniferous age. Within the areas the presence of molybdeniferous soils and pasture is related to local variation in geology and parent material and is in particular affected by drift cover.Blood copper analysis on 350 cattle from 26 herds, excluding those herds in which deficiency was previously recognized, indicated hypocupraemia in 64% within the geochemically denned molybdeniferous area compared to 35 % in nearby control areas. Excluding animals fed minerals, the results were 77 and 37%, respectively. On the whole, deficient animals showed no marked clinical symptoms of hypocuprosis, though unthriftiness and poor fertility are common in the area.

SUMMARYCopper supplementation within the molybdenum-rich areas, on an exploratory basis in 1967 and in controlled trials in 1968, showed mean live-weight responses of 10–70% in dairy followers representing mean herd increases due to copper of 30–70 lb per animal over a 6-month grazing period. With few exceptions control stock showed no clinical symptoms of hypocuprosis.

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