There was no significant treatment effect on calf growth rate overall, however in the herd that showed marginal cobalt levels in stock there was a significant treatment effect. It is possible that the treatment effect was related to treatment of cobalt deficiency in this herd. If each calf was sold for a $1.75kg live weight, this would equate to a difference of $13.90 between treatment and control calves at the time then second weighing in this herd, which was 311 days after the first weighing. In remaining herds there was no economic benefit of treatment, even in those herds in which calves were blood tested with marginal or deficient levels of copper or selenium. Those members who retained heifers as breeders from the trial calves have found no difference in weight gain or pregnancy rates between the control and the treated heifers.