Effect of supplemental trace mineral complexes on rectal temperature, feed intake and body weight change with infectious bovine rhinotracheitis virus challenged feedlot cattle

Abstract

Experiments were conducted using feedlot steers in a randomized block design to determine the effect of Zn and Cu complexes on feed intake and rectal temperature of cattle stressed with Infectious Bovine Rhinotracheitis virus (IBRV). Cattle were adapted for 7 d to the experimental diets after a 35 d adaptation to the basal ration and challenged with 3.7 X 10^5 plaque forming units of IBRV on d 0 of each experiment. Live weights (BWT), rectal temperature (RT) and individual daily feed intake (FI) was recorded for 14 d post-challenge. In Exp. 1, Zinc methionine (ZnM; Zn = 71 ppm) reduced (P < .05) mean RT when compared to Control (C; Zn = 42 ppm) with Zinc proteinate (ZnP; Zn = 71 ppm) and Zinc sulfate (ZnS; Zn = 76 ppm) intermediate on d 6 and 7. Mean FI was higher (P < .05) for ZnM on d 8 when compared to C. Serum Zn levels were higher (P < .05) for ZnS on d 7 when compared to C. Serum Cu was higher (P < .05) in ZnP compared to C. In Exp. 2, Copper proteinate (CuP; Cu = 21 ppm) elicited lower (P < .05) mean RT on d 4, 6 and 7 when compared to Control (C; Cu = 10 ppm) with Copper sulfate (CuS; Cu = 21 ppm) intermediate. Both CuS and CuP exhibited higher (P < .05) serum Zn concentrations when compared to C on d 7. Experiment 3 compared the solubility of trace mineral compounds. Complexes were analyzed for % solubility (PS) of Zn and Cu respectively. Zinc methionine exhibited higher (P < .05) PS when compared to other treatments at 250 and 500 ppm concentrations at pH 5.0 followed by ZnS, ZnP and ZnO, each of which was lower ( P < .05) than it's predecessor. Level of pH affected PS with all treatments having greater (P < .05) PS at pH 5.0 when compared to other levels. Copper complexes were affected by treatment and pH with CuP eliciting higher (P < .05) PS when compared to CuS at all pH levels except 5.0. These data suggest that feeding different forms and levels of Zn and Cu affects feed intake and rectal temperature of IBRV challenged cattle. This effect could be due to differing bioavailabilities of the compounds. The solubility of these complexes may be involved with bioavailability.