CHRONIC COPPER TOXICITY IN LAMBS: A SURVEY OF BLOOD CONSTITUENT RESPONSES

Abstract

Blood chemistry of lambs was studied during the period of liver copper accumulation in chronic copper toxicity. In trial 1, dietary copper was 10.9, 17.8 and 25.2 mg/kg. During a 10-wk feeding trial no mortalities due to copper toxicity and no differences in growth rate were found (P > 0.05). At slaughter, liver copper levels were 239, 454 and 721 μg/g of dry matter, respectively (P < 0.05). There was no response to added dietary copper for hematocrit, ferroxidase, aspartate aminotransferase, allantoin, plasma protein, catalase, molybdenum or plasma copper (P > 0.05). In trial 2, dietary copper was 9.1 and 37.3 mg/kg. Lambs were individually fed for an 11-wk feeding trial. No mortalities or difference in growth occurred (P > 0.05). At slaughter, liver copper levels were 372 and 1109 μg/g of dry matter, respectively (P < 0.05). Plasma aspartate aminotransferase was elevated in response to added dietary copper (P < 0.05). No effect due to added dietary copper was found with superoxide dismutase, alkaline phosphatase, ferroxidase, lactate dehydrogenase, plasma protein, hemoglobin, plasma copper, calcium, inorganic phosphate, cholesterol, triglyceride, uric acid, urea nitrogen or hematocrit (P > 0.05). Only plasma aspartate aminotransferase and liver copper concentration could be considered useful indicators of high copper status.