Influence of pre-weaning trace mineral exposure on subsequent performance and trace mineral status of beef calves during finishing

Objectives of these experiments were to 1) evaluate the accu­mulation of Co, Cu, Mn and Zn in liver tissue during the fin­ishing period of calves with or without previous mineral sup­plement exposure; and 2) evaluate the performance of calves provided either organic or inorganic sources of Co, Cu, Mn and Zn. One-hundred twenty steers of unknown mineral history, and 48 steers of known mineral history prior to weaning were comin­gled in experiment 1. Steers were allocated to pens and assigned to receive either an inorganic or organic trace minerals. For experiment 2, 83 steers with or without exposure to mineral supplements during gestation and the subsequent lactation, were utilized in a 181-d finishing experiment. ADG tended to be greater (P = 0.09) during the first 53 days on feed in calves provided organic trace minerals. Calves with trace mineral access prior to weaning were heavier at the time of feedlot arrival (P = 0.06), but not at slaughter (P = 0.37). Pro­viding access to mineral supplements to cow-calf pairs dur­ing grazing increased (P < 0.01) Cu and Co, but did not affect (P ≥ 0.29) Zn or Mn concentrations at feedlot arrival. Liver Cu status improved during backgrounding in steers fed the or­ganic trace minerals. For calves of known mineral history, providing access to mineral sup­plements during grazing, prior to weaning, had no impacts on subsequent gain or intake during growing and finishing. Providing organic forms of trace minerals tended to improve growth early in the feeding period.