Treatments consisted of two different free choice mineral supplements (Table 1). The control mineral supplied all trace elements in inorganic form. The organic mineral supplement supplied two-thirds of the zinc, copper, manganese and cobalt as zinc methio nine, copper lysine, manganese methionine and cobalt glucoheptonate (4-Plex-C®) respectively. There were three replicate groups of cattle per treatment.
Steers were rotated among the six pastures weekly to correct for differences that may have existed among pastures. Two consecutive body weights were ob tained at the beginning and termination of the 112-day study. Interim weights were taken at 28-day intervals. Plasma samples were collected on days 0, 56 and 112 for zinc and copper analyses.
Steer gains, mineral intake and an economic analysis are shown in Table 2. For the entire 112-day study, steers receiving the organic mineral tended to gain 4.6% faster than controls, but the difference between treatments was not statistically significant.
Mineral consumption for steers fed the control supplement was 3.8 oz/day. Mineral consumption by steers offered the organic mineral resulted in an average intake of 2.83 oz per day. Of this, 0.226 oz per day was of the concentrated trace mineral source (4-Plex-C®), which is close to the targeted consump tion of .25 ounces per day. Intake of zinc, copper, manganese and cobalt from organic sources averaged 318, 89, 180 and 25 mg per day, respectively.
Assuming that the difference observed among treatments is repeatable, and was due to the different mineral supplements, the cattle on the organic trace mineral supplement returned $2.14/head more than those on the control supplement. Based on this, we could have paid $11.70 more per 50 lb bag of the organic trace mineral supplement than we paid for the inorganic one and still have broken even. Because the differences observed were not statistically significant, however, additional studies need to be conducted before a clear recommendation can be made.