Abstract
Sixty crossbred pigs averaging 8.9 kg body weight initially were used in a 9-week study to determine if a higher than recommended dietary level of iron is beneficial when high dietary copper levels are fed and to determine if the copper requirement is increased when the diet contains higher than normal dietary levels of iron. A 2 × 3 factorial design was employed utilizing iron levels of 101 and 312 ppm and copper levels of 7, 25 and 257 ppm. Feeding 257 ppm dietary copper significantly increased weight gain and feed intake during the first 4 weeks with no improvement in the gain/feed ratio. A dietary copper level of 257 ppm reduced hemoglobin and serum iron levels when the dietary iron level was 101 ppm, whereas, these parameters were maintained normally when the diet contained 312 ppm iron. The low copper-high iron diet produced a high serum iron level which would indicate that 7 ppm dietary copper is adequate for normal iron metabolism. Serum copper levels were significantly increased at weeks 3 and 6 by the highest dietary level of copper regardless of the iron level. Copper accumulated in the liver, kidney and hair when the pigs were fed diets containing 257 ppm copper. When the diet contained 312 ppm iron the accumulation of copper in the liver was reduced. The iron content of liver, spleen and kidney was increased (P<0.05) when the diet contained 25 ppm copper; whereas, the iron content of these tissues was decreased when the diet contained 257 ppm copper. There was no effect of dietary copper and iron on the zinc content of the liver, spleen and kidney. The metacarpal content of copper, iron and zinc was not influenced by the dietary copper and iron levels. Higher than National Research Council's recommended level of dietary iron allowed the maintenance of normal hemoglobin values and serum iron levels and reduced liver copper stores when high dietary copper levels were fed for growth stimulation. Copyright © 1973. American Society of Animal Science. Copyright 1973 by American Society of Animal Science

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