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Effect of Elevated Dietary Levels of Iron on the Performance and Blood Constituents of Calves¹

North Carolina State University, Raleigh²

Abstract

Fifty-six Holstein male calves were used in two experiments to determine the minimum toxic level of iron and the effect of high levels of dietary iron on performance and blood constituents. A ration compounded from natural feedstuffs and containing 100 ppm iron was used as the basal in both experiments. Ferric citrate was added to the basal ration to give the desired iron levels. In Experiment I the levels of iron were 100, 500, 1,000 and 2,000 ppm. Six individually fed calves received each of the four rations during a 70-day experimental period. Blood hemoglobin and serum iron were significantly increased at the high dietary levels of iron. Serum inorganic phosphorus was significantly depressed as dietary iron increased. No significant difference was found between treatments in weight gain, feed intake and feed conversion or in serum calcium, magnesium, alkaline phosphatase activity, copper and zinc. In Experiment II, the levels of iron were 100, 1,000, 2,500 and 4,000 ppm. Eight calves were individually fed each of the four rations for 98 days. No significant difference was found in serum calcium, magnesium, copper, or zinc. Significant depressions in weight gain, feed intake, and serum inorganic phosphorus were noted with increasing dietary iron. Feed necessary per pound of gain, blood hemoglobin, and serum iron were found to be increased with increasing dietary iron. The maximum level of dietary iron which the calf may consume without marked depression in feed intake and body weight gain appears to be approximately 2,000 ppm.

¹ Paper No. 2939 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, North Carolina.

² Animal Science Department.