A Study of Iron and Copper Requirements of Dairy Calves

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Abstract
Male calves were used in this study. The basal diet consisted of whole milk, supplemented with vitamins A and D, Co, and Mg. Three levels of supplemental Fe, O, 30, and 60 mg/day, and 3 levels of supplemental Cu, O, 3, and 6 mg/day, were studied in a 3 x 3 factorial design. In the 1st of 2 trials, 9 calves were started on the treatments at 2 days of age. In the 2d trial, 18 calves were fed the basal diet until the hemoglobin (Hb) level declined to 5-6 g/100 ml of blood, and then were placed on the treatments. Animals on the zero level of supplemental Fe became anemic and gained less than those on the other 2 levels. Calves fed either 30 or 60 mg of Fe in Trial 1 main-tained normal levels of Hb and of red-cell volume. The Hb level of calves receiving supplemental Fe in Trial 2 increased from a mean value of 5.4 g to 8.0 g/100 ml during a period of 16-20 weeks. Hb 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 Fe were utilized. The minimal nutritional Fe requirement for maintenance of a normal Hb level in growing calves was estimated to be about 30 mg/day. Different dietary levels of Cu did not influence Hb concentration.
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