Comparison of injectable trace minerals vs. adjuvant on measures of innate and humoral immune responses of beef heifers

Abstract

• Injectable trace minerals (ITM), adjuvant (ADJ) and saline did not impact calf growth • Haptoglobin and ceruloplasmin were greatest for ADJ but similar between SAL and ITM • ITM enhanced calf antibody titers but not to the extent as ADJ injection Previous studies reported heightened innate and humoral immune responses among cattle administered injectable trace minerals (ITM) concurrent to immunogen challenge, thus suggesting a potential adjuvant-like activity of ITM. To pursue this concept further, a two-year study was conducted at the Mountain Research Station (North Carolina State University, Waynesville) to evaluate immunological responses of Angus heifers (n = 22, 235 ± 18 kg of BW and 225 ± 4 d of age in yr 1; n = 36, 237 ± 6 kg of BW and 247 ± 5 d of age in yr 2). On d 0 (30 days after weaning), heifers were administered two 5-mL i.m. injections of porcine red blood cells (PRBC; Lampire Biological Laboratories, Pipersville, PA) solution (25% PRBC and 75% sterile PBS; Amresco, Solon, OH), concurrent to either a single 2.5-mL s.c. injection of sterile saline (SAL; 0.9% NaCl), a squalene-based oil-in-water adjuvant (ADJ; AddaVax; InvivoGen, Inc. San Diego, CA) that specifically induces a humoral immune response, or injectable trace minerals (ITM; MultiMin 90; MultiMin USA, Inc. Fort Collins, CO; 60, 10, 15 and 5 mg/mL of Zn, Mn, Cu and Se). During the 28-d study, heifers were offered tall fescue hay ( Lolium arundinacea ) and concentrate at 1.2 and 1.0% of BW (DM basis), respectively, blended with 114 g daily of a complete mineral mix. Shrunk BW was recorded on d 0 and 28 following 12 h of feed and water withdrawal. Blood samples were collected on d 0, 2, 7, 15, and 21 for determination of antibody titers against PRBC and plasma concentrations of ceruloplasmin and haptoglobin. Liver biopsy samples were collected 1 mo prior to weaning and on d 15 after weaning for determination of trace mineral status. No differences were detected ( P ≥ 0.13) for BW change, ADG, G:F, or DMI. Liver Se concentrations on d 15 were greater ( P ≤ 0.01) for heifers receiving ITM compared to SAL and ADJ treatments. Plasma haptoglobin concentrations on d 2 were greatest for ADJ ( P < 0.0001) and did not differ between SAL and ITM heifers ( P ≥ 0.46). Plasma ceruloplasmin concentrations on d 2 were greatest for ADJ ( P ≤ 0.04) and did not differ between SAL and ITM heifers ( P = 0.39). On d 7, plasma concentrations of ceruloplasmin did not differ ( P = 0.37) between ADJ and ITM, were less for SAL vs. ADJ ( P = 0.005), and tended to differ ( P = 0.064) between ITM and SAL heifers. Serum PRBC titers were greatest for ADJ ( P ≤ 0.03) vs. SAL on d 7, 15, and 21 and ITM on d 7 ( P < 0.001). Serum PRBC titers did not differ between SAL and ITM on d 7 and 15 ( P ≥ 0.23), but were greater in ITM vs. SAL on d 21 ( P = 0.03). In summary, ITM prolonged the antibody titers against PRBC on d 21 compared to saline injection in mineral-adequate beef calves, but not as quickly or to the extent of ADJ injection.