Effect of trace mineral supplementation on clinical signs, immune response variables, and mineral balance of calves following exposure to bovine viral diarrhea virus and subsequent Mannheima haemolytica infection
The objective was to determine the influence of copper (Cu), manganese (Mn), and zinc (Zn) supplementation on the clinical signs, immune response variables, and mineral balance of calves following a bovine viral diarrhea virus (BVDV) and Mannheima haemolytica (MH) immune challenge. Steers (n = 16; BW = 225 ± 20 kg) from a single ranch were processed, weaned, and randomly pairwise assigned to either the mineral supplemented (MIN) or control (CON) experimental treatments. The MIN calves received 150 mg of Cu, 130 mg of Mn, and 360 mg of Zn daily while the CON calves received the basal diet with no additional Cu, Mn, or Zn supplementation. The basal diet contained sufficient Mn and Zn, but inadequate Cu based on published nutrient requirements. After 46 d on the experimental treatments, all calves were naturally exposed to BVDV type 1b for 4 d and subsequently infected with MH. Data were analyzed using the GLM procedure of SAS with sampling time serving as a repeated measure. Calf served as the experimental unit. The immune challenge was validated via increased (P < 0.001) BVDV antibody titers, MH whole cell (WC) and leukotoxin (LKT) antibody titers, rectal temperatures (TEMP), and subjective clinical scores (CS). A time by treatment interaction was observed for BVDV and MHWC antibody titers (P ≤ 0.04). Calves receiving MIN had reduced (P = 0.03) BVDV antibody titers, but increased (P = 0.02) MHWC antibody titers compared to CON calves. Mineral supplementation did not impact CS, TEMP, or MHLKT antibody titers (P ≥ 0.48). There was a significant (P < 0.001) time by treatment interaction observed for liver Cu levels. Time significantly impacted the concentrations of Cu, Mn, Fe, and Zn within the liver and Cu, Zn, and Fe within the muscle and serum (P ≤ 0.03). Calves receiving MIN had greater liver Cu (P < 0.001) and Mn (P = 0.04) concentrations compared to CON calves. In contrast, serum Cu concentrations were increased (P = 0.02) in CON calves compared to MIN calves. Mineral supplementation did not impact mineral levels within the muscle samples (P ≥ 0.20). The supplementation of Cu, Mn, and Zn may potentially impact the antibody response to a BVDV and MH immune challenge in calves. When Cu is supplemented to calves receiving a marginally Cu deficient diet, Cu status within the body can be altered.
bovine respiratory disease