The Effect of Trace Minerals on Growth Performance and Vitamin B12 Synthesis of Steers

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Abstract
In each of two feeding experiments, steer calves were individually fed a ration of mature timothy hay, ground ear corn, urea, cerelose, calcium, phosphorus, iodized salt, and vitamin A. A trace mineral supplement (cobalt, manganese, zinc, iron, and copper) or alfalfa ash significantly increased the average daily gains of the steers. Studies to determine which one of the trace minerals was responsible for the growth stimulation indicated that cobalt was the first limiting trace mineral deficiency although the possibility that other minerals, e.g. manganese, may be beneficial is not excluded. Besides improved gains, feeding cobalt or a cobalt-containing supplement significantly increased the cobalt and vitamin B12 content of the liver, and the amount of vitamin Big excreted in the feces. Based on ration analyses, it was calculated that the average cobalt content of the ration was 0.03–0.04 p.p.m. Feed intake, chiefly ground ear corn, was significantly increased (one experiment) and there was a trend toward more efficient use of feed by the trace mineral, alfalfa ash, or cobalt-fed steers but the differences were not significant. The results of one digestion trial using the chromic oxide marker technique indicated that the apparent digestibility of the ration was unaffected by the mineral supplements. Possible explanations for these findings are discussed.