Effects of organic or inorganic Co, Cu, Mn, and Zn supplementation to weaned calves during preconditioning on their productive and health responses

Abstract Text: This experiment compared productive and health parameters of weaned calves receiving or not supplemental Co, Cu, Mn, and Zn from an organic or inorganic source during a 45-d preconditioning program. Ninety Angus × Hereford calves were weaned on d -1 and immediately allocated according to weaning BW and age (BW = 261 ± 2 kg, age = 224 ± 2) to a18-pen drylot with 5 calves per pen (steers, n = 4; heifers, n = 1). Pens were randomly assigned to receive: 1) supplementation with inorganic sulfate sources of Cu, Co, Mn, and Zn (INR), 2) supplementation with an organic source of Cu, Mn, Co, and Zn (ORG; Availa^®4; Zinpro Corporation, Eden Prairie, MN), and 3) no supplementation of Cu, Co, Mn, and Zn (CON). During the preconditioning phase (d 0 to 45), calves received mineral treatments while offered free-choice hay and 2.7 kg/d of corn-soybean meal concentrate. The INR and ORG were included into the concentrate, and formulated to provide the same daily amount of Cu, Co, Mn, and Zn. Calf ADG during preconditioning was calculated based on average initial BW (d -1 and 0) and final BW (d 44 and 45). Liver samples were collected via needle biopsy on d 0, 22, and 45. Calves received vaccination on d 15 and 29. Blood samples were collected on d 15, 29, and 45, and analyzed for plasma concentrations of antibodies against Mannheimia haemolytica. No differences were detected (P ≥ 0.15) among CON, INR, and ORG calves for initial (d 0) liver Co, Cu, Mn, and Zn concentrations. On d 22 and 45, liver Cu and Co concentrations were greater (P < 0.01) for INR and ORG calves compared with CON. Moreover, ORG calves had greater (P = 0.05) liver Co concentrations on d 45, but similar (P = 0.35) liver Co on d 22 and similar (P ≥ 0.63) liver Cu on d 22 and 45 compared with INR calves. Liver Zn and Mn concentrations were similar (P ≥ 0.14) among CON, INR, and ORG calves on d 22 and 45. No differences (P ≥ 0.17) were detected among treatments for feed intake, BW gain, health variables, or antibodies against M. haemolytica. Therefore, supplementation with inorganic or organic Co, Cu, Mn, and Zn during a 45-d preconditioning period did not impact performance and health response of weaned feeder calves.

Keywords: beef cattle, performance, preconditioning, trace minerals