Manganese in the Nutrition of Young Dairy Cattle Fed Different Levels of Calcium and Phosphorus

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Abstract
In a study of Mn in ruminant nutrition 15 calves were assigned at random to the following diets: (1) basal (Mn content less than 1 ppm); (2) basal + Mn (50 ppm); (3) basal + 3 to 5% Ca(H2PO4)2-H2O; (4) basal + a combination of the supplements in 2 and 3; and, (5) conventional type (control). Growth rate and serum Mg levels of the control group were greater than for calves fed other diets. Supplemental Mn did not affect (P < 0.05) the levels of Ca and inorganic P and the activity of alkaline phosphatase in blood serum. Conversely, supplemental Mn partially counteracted the deleterious effects of Ca(H2PO4)2-H2O on gain during the latter part of the study, depressed serum Mg, increased blood levels of Mn and increased the life span, which was decreased by Ca(H2PO4)2-H2O. The effect of supplemental Mn on serum Mg levels was greatest on blood Mn levels, was least in the presence of supplemental Ca(H2PO4)2-H2O. Mortality among calves fed diets 1, 2, 3 and 4 was 100%. Postmortem examinations revealed calcified deposits in the cardiovascular or pulmonary system of all calves fed diets 2, 3 and 4, but none in calves fed diets 1 and 5. Uncomplicated Mn deficiency was not demonstrated in the calves, but the need for dietary Mn apparently is extremely low and is increased by supplemental Ca and P.
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