The effects of zinc hydroxychloride and basic copper chloride on growth performance, carcass characteristics, and liver zinc and copper status at slaughter in yearling feedlot steers1

Several trace mineral sources are available for use in feedlot diets. This study was conducted to provide nutritionists with information supporting the formulation of more cost effective trace mineral supplementation programs. Crossbred yearling steers (n = 288, initial BW = 319 ± 10.2 kg), housed in 32 pens (8 pens per treatment), were used in a randomized complete block design experiment to compare the effects of Zn hydroxychloride and basic Cu chloride, fed at 2 concentrations, to Zn and Cu sulfate or Zn and Cu sulfate plus Zn and Cu amino acid complexes on feedlot performance, carcass merit, and liver mineral status at slaughter. Treatments (100% DM basis) included 90 mg/kg of Zn from Zn sulfate and 15 mg/kg of Cu from Cu sulfate; 67.5 mg/kg of Zn from Zn sulfate plus 22.5 mg/kg of Zn from Zn amino acid complex (Availa Zn; Zinpro Corporation, Eden Prairie, MN) and 11.25 mg/kg of Cu from Cu sulfate plus 3.75 mg/kg of Cu from Cu amino acid complex (Availa Cu; Zinpro Corporation); 90 mg/kg of Zn from Zn hydroxychloride (IntelliBond Z; Micronutrients, Indianapolis, IN) and 15 mg/kg of Cu from basic Cu chloride (IntelliBond C; Micronutrients); and 54 mg/kg of Zn from Zn hydroxychloride and 9 mg/kg of Cu from basic Cu chloride. No significant (P > 0.10) treatment differences were found for initial, d-28, or final BW. Average daily gain, DMI, G:F, NE recovery, carcass characteristics, and liver Cu and Zn concentrations at the time of slaughter did not differ (P > 0.10) among treatments. These results indicate that Zn hydroxychloride and basic Cu chloride were effectively absorbed and used by yearling steers and can be fed at a reduced rate compared with current industry feeding practices without negative effects on feedlot performance, carcass merit, and liver Zn and Cu status.