Effects of Zinc, Copper, and Manganese Supplementation of High-Concentrate Ratio on Gastrointestinal Absorption of Copper and Manganese in Holstein Calves

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Abstract
Holstein bull calves (16) were fed a high-concentrate ration supplemented with Zn, Cu and Mg, alone or in combination, for 10 wk. After 6 days of preliminary feeding of chromic oxide, fecal grab-samples were collected for 6 days. Calves were slaughtered, and samples of the contents of the reticulo-rumen, omasum, abomasum, small intestine, cecum and large intestine were analyzed for chromic oxide, Cu and Mg. Absorption along the gastrointestinal tract, measured by comparison of 1 segment with the previous segment, indicated net secretion of Cu in the abomasum but net absorption from the rest of the tract. The exception was that net secretion into the reticulo-rumen was associated with low dietary Cu. Net secretion of Mg was mainly in the small intestine and cecum in all treatments. A higher proportion of Cu apparently was absorbed when this mineral was supplemented in the ration. Absorption of Mn was decreases slightly when Mg was supplemented in the ration. Reabsorption of Mg in the large intestine was probably greater than that of Cu.