Copper deficiency is a widespread problem in beef cattle. Factors affecting copper requirements of beef cattle are not well understood. The present study evaluated copper status in different beef cattle breeds.
Materials and Methods
Thirty-eight heifers (11 Angus, 8 Charolais, and 19 Simmental) in the last trimester of pregnancy were used in this study. Heifers were fed corn silage supplemented with protein, in confinement pens, until their calves were weaned. Calves also had access to the corn silage-based diet. Cattle within each breed were supplemented with either control (no supplemental copper, iron or molybdenum), 600 ppm of iron, 5 ppm of molybdenum or 10 ppm of copper. The diets not supplemented with copper contained 4 ppm of copper which is well below the recommended level of 8 ppm. The iron and molybdenum treatments were included because both of these minerals are known to reduce copper status in cattle
Blood samples were obtained from heifers at 28-day intervals throughout the 280-day study. Calves were born between days 70 and 125 of the study. Blood samples were collected from calves at 28-day intervals beginning on day 168 of the study. Blood samples were used for plasma copper determination.
Results and Discussion
There were few differences in plasma copper concentrations among breeds when heifers were supplemented with 10 ppm of copper. Heifers receiving supplemental copper remained in adequate copper status throughout the study based on plasma copper concentrations.
When supplemental copper was not fed, Angus heifers had greater plasma copper concentrations than Charolais and Simmental heifers from day 28 until 140 of the study. Plasma copper concentrations were lowest during gestation and increased following calving in all breeds.
Plasma copper concentrations in calves fed supplemental copper are shown in Table 1. Angus calves had higher plasma copper levels than Charolais and Simmental calves throughout the study. Plasma copper concentrations were generally similar in Charolais and Simmental calves. Copper levels in plasma greater that .6 mg/L are indicative of adequate copper status in cattle. This would suggest that Angus calves were adequate in copper while Simmental and Charolais may have been marginal in copper status.
Calves born to heifers not receiving supplemental copper were copper deficient based on the low plasma copper values obtained (Table 2). However, Angus calves had higher plasma copper concentrations than Simmental calves on all sampling dates. Plasma copper levels in Charolais calves were intermediate and did not differ significantly from those observed in Simmental calves.
Simmental and Charolais cattle had lower copper status based on plasma copper concentrations than Angus cattle when fed identical diets. These results suggests that Simmental and Charolais cattle have higher copper requirements than Angus.
|Table 1. Plasma Copper Concentrations of Angus, Charolais, and Simmental Calves Fed Supplemental Copper|
|a,b Means within a row lacking a common superscript letter differ (P<.05).|
|Table 2. Plasma Copper Concentrations of Angus, Charolais, and Simmental Calves Not Fed Supplemental Copper|
|a,bMeans within a row lacking a common superscript letter differ (P<.05).|
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