Effect of copper and zinc source on finishing performance and incidence of foot rot in feedlot steers

ABSTRACT A commercial feedlot study was conducted to compare a combination of inorganic and organic copper and zinc trace minerals (CON) to basic copper chloride and zinc hydroxychloride trace minerals (BCHZ) on performance, carcass characteristics, and incidence of foot rot in feedlot cattle. Crossbred steer calves (n = 1,471, initial BW 273 ± 10 kg) were housed in 16 pens with average head count of 92 steers (71 to 159 steers) per pen. Pens were blocked by origin and assigned randomly to 1 of 2 treatments (8 pens per treatment). Treatments consisted of adding 25 (growing) or 19 (finishing) mg/kg of copper and 136 (growing) or 108 (finishing) mg/kg of zinc to the diet. The CON consisted of copper sulfate and 65% zinc sulfate and 35% zinc methionine, whereas BCHZ consisted of basic copper chloride and zinc hydroxychloride trace minerals. Data were analyzed using the Glimmix procedure of SAS. There was a 4-kg significant difference in initial BW; thus, initial BW was used as a covariate. There were no differences in DMI, ADG, final BW, or G:F (P ≥ 0.14). Hot carcass weight, DP, and USDA QG also were unaffected (P ≥ 0.17) by source of trace mineral supplementation. There were no differences (P ≥ 0.28) in total morbidity or foot rot treatments in terms of total number of pulls or re-treated animals when comparing CON with BCHZ. Cattle that received basic copper chloride and zinc hydroxychloride trace mineral supplement performed similar to cattle that received a conventional mineral program.