A silent hypocupremic condition in beef cows fed grass silage and the efficacy of sequestered copper to prevent its occurrence.
Three groups of 18 Shorthorn cows were fed, as a sole maintenance diet, grass silage known to produce hypocupremia. Two of these groups were comprised of pregnant cows and the third group of non-pregnant cows. In late Fall, the cows were grouped in inside pens and had free access to a mineral feed. In the mineral feed offered to one of the groups of pregnant cows, 0.25% of sodium chloride was replaced by sequestered copper. The non-supplemented group of pregnant cows showed a decrease in blood plasma copper over wintered and in April, more than half of the animals in this group were hypocupremic. The average copper intake (in the form of sequestered copper) from the mineral feed of 8.7 mg/cow/day was sufficient to prevent the onset of hypocupremia in four-fifths of the cows in the supplemented group. The non-supplemented, non-pregnant group maintained normal blood plasma copper level throughout winter confinement. On release to pasture in early summer, cows in all groups of cows showed upwards trends in blood plasma copper level. At the end of the pasture season the blood plasma copper levels in all groups of cows were normal. Hematological and morphological studies showed that hematopoiesis of the hypocupremic cows were not affected and that they were not suffering from microcytic hypochromic anemia. It was suggested that the soluble proteins in the grass silage reduced the amount of copper available in vivo. This, together with the heavy physiological demand of copper imposed upon the cows by pregnancy, resulted in hypocupremia.
D000284:Administration, Oral; D000821:Animal Feed; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D003300:Copper / Q000008:administration & dosage / Q000097:blood / Q000172:deficiency*; D005260:Female; D007501:Iron / Q000097:blood; D006109:Poaceae; D012820:Silage / Q000032:analysis
D003300:Copper; D007501:Iron