Effects of copper source and concentration on copper status and immune function in growing and finishing steers

Abstract Forty-eight individually fed purebred Angus steers (7±1.1 mo of age, 218±9.1 kg BW) were used to determine the effects of copper (Cu) source and concentration on Cu status and immune function. Steers were stratified by weight and initial liver Cu concentration and randomly assigned to one of five treatments. Treatments were: (1) control (no supplemental Cu), (2) 10 mg Cu/kg dry matter (DM) from Cu sulfate (CuSO 4 ), (3) 10 mg Cu/kg DM from a Cu-amino acid complex (Availa Cu; Zinpro Corporation, Eden Prairie, MN, USA), (4) 20 mg Cu/kg DM from CuSO 4 , and (5) 20 mg Cu/kg DM from Availa Cu. Steers were housed in individual pens and fed an alfalfa-corn based growing diet (7.1 mg Cu/kg DM) for 56 d then gradually switched to a high concentrate diet (6.1 mg Cu/kg DM) for 144 d. On d 56 of the growing phase and d 112 of the finishing phase, liver Cu concentrations were higher ( P P P 4 . Cell mediated immune response to phytohemagglutinin was higher ( P P 4 than steers supplemented with 10 mg Cu/kg DM from Availa Cu. During the finishing phase, IgG concentrations specific to PRBC were higher ( P P P P 4 . Results indicate that the immune response to an antigen varies depending on the type of antigen administered as well as the concentration and source of Cu supplemented.