A Study of Iron and Copper Requirements of Dairy Calves

Abstract

Twenty-seven male Holstein calves were used in a study to determine iron and copper requirements.The basal diet consisted of whole milk, supplemented with vitamins A and D, cobalt, and magnesium. The investigation was conducted in two trials, in which three levels of supplemental iron, 0, 30, and 60 mg. per day, and three levels of supplemental copper, 0, 3, and 6 mg. per day, were studied in a 3 × 3 factorial design involving a total of nine treatments. In the first trial, nine calves were started on the experimental treatments at 2 days of age. In the second trial, 18 calves, two replications, were fed the basal diet until the hemoglobin level declined to 5-6 g. per 100 ml. of blood, and then were started on the experimental treatments. The results were as follows: Animals on the zero level of supplemental iron became anemic and gained less than those on the 30 mg. and the 60 mg. intakes of iron per day. Calves fed either 30 mg. or 60 mg. of iron in Trial 1 maintained normal levels of hemoglobin and of red-cell volume. The hemoglobin level of calves receiving supplemental iron in Trial 2 increased from a mean value of 5.4 g. to 8.0 g. per 100 ml., during a period of from 16 to 20 wk. No difference was obtained in hemoglobin levels between the 30 mg. and the 60 mg.levels of iron intake. Hemoglobin levels and calculated utilization values indicated that on the average approximately 60% of the 30 mg. level and 30% of the 60 mg. level of iron were utilized. The data from this investigation indicate that the minimal nutritional iron requirement for maintenance of a normal hemoglobin level in growing calves is approximately 30 mg. per day. Without supplemental copper in the diet, the serum-copper decreased, but an intake of 6 mg. of copper per day was sufficient to restore or to maintain a normal level of serum copper. Different dietary levels of copper did not influence hemoglobin concentration under the conditions of the experiment. © 1957, American Dairy Science Association. All rights reserved.