100 Evaluating the effect of liver copper concentration on vaccine response in lightweight dairy-beef steers

Abstract

Abstract Dairy-beef crossbred calves often face greater copper (Cu) exposure than native beef calves, which may impact their response to vaccines. To investigate this, 28 weaned dairy-beef steers (90.25 ± 1.28 kg; ~8 wk old) were enrolled in a study to determine the effect of Cu status on the antibody response to vaccine. Steers were stratified by body weight (BW) and assigned to one of two dietary treatments: low Cu (no supplemental Cu) and high Cu (supplementing 20 mg Cu/kg DM). Steers were housed in pens of six to eight animals for 82 d before d 0 of the vaccination period to create distinct liver Cu groupings. Seven days before initial vaccine dose, liver biopsies were collected, and steers were grouped into low (n = 13) and high (n = 15) Cu treatments. Liver Cu for low Cu averaged 291 ± 24 mg/kg DM (range 240 to 376 mg/kg DM) and for high Cu averaged 665 ± 23 mg Cu/kg liver DM (range 519 to 893 mg/kg DM). All calves were vaccinated on d 0 and boostered 21 d later with Bovilis Vista 5 SQ (Merck Animal Health, Rahway, NJ) and an ovalbumin vaccine. Blood and BW were collected on these days and again on d 49 to end the study. Serum antibody titers for BRSV, BHV1, BVDV1, and BVDV2 were analyzed by the Iowa State University Veterinary Diagnostic Laboratory (Ames, IA). Response to ovalbumin vaccination was determined using an ELISA. Plasma Cu concentrations were determined on d 0, 21, and 49 via ICP-OES. Ovalbumin antibodies were determined by calculating the ratio of each sample to a positive control. Titers, ovalbumin response, and plasma Cu data from d 0, 21, and 49 were analyzed using the Mixed procedure of SAS 9.4 (Cary, NC) with the fixed effect of Cu treatment and day as repeated. Plasma Cu decreased across days (P = 0.0008). Given both treatments had adequate liver Cu, it is unsurprising plasma Cu did not differ by treatment (P = 0.2; 1.02 and 1.07 mg Cu/L for low and high Cu, respectively). Antibodies for BRSV, BHV1, and BVDV2 increased across days (P < 0.0001), but there were no differences by treatment (P ≥ 0.12). Ovalbumin antibodies were affected by treatment by day (P = 0.04), where high Cu had greater response to ovalbumin than low Cu on d 21, but by d 49 ovalbumin antibodies were similar between Cu treatments. These results suggest excessive liver Cu concentration may not affect response to vaccination in dairy-beef steers; however, more research is needed to determine the effects of increased liver Cu concentration on oxidative stress and immune system function.