| Abstrakt: |
Two groups of five female Hereford calves were fed grass silage prepared with sugar beet molasses, grain, limited hay, and offered dicalcium phosphate, steamed bone meal and plain salt on a free choice basis. One group served as controls while the other received copper sulfate, cobalt carbonate, and magnesium sulfate offered free choice, mixed with common salt.The control group gained 1.76 lb. per day while the group having free access to trace minerals gained 2.11 lb. per day. This difference proved statistically significant at the 10% probability level.Increased total ration consumption was noted in the animals receiving the trace mineral supplement.On the diets listed, the animals having free access to magnesium, copper and cobalt salts averaged an intake of 60, 17.3 and 0.6 mg. per day, respectively.Whole blood and plasma copper values did not consistently reflect the. low liver values of either group. Extremes in high and low liver copper at the start of the experiment were, however, accompanied by extremes in blood copper.There was a slight increase in liver copper content for both groups. The difference in the final copper content between control and supplemented groups was significant at the 5% level.Liver iron storage decreased while copper storage increased.The animals did not show an ability to correct their low level copper stores through free choice selection of a copper-containing salt mixture. |
