80 Effect of copper bolus administration on circulating copper concentration, blood metabolites and parasite load

Abstract

Abstract In Texas and Southeastern United States Cu concentration in the soil is in the lower 50th percentile, this leads low bioavailability of copper for livestock. Therefore, a 70-d completely randomized block design study was conducted to determine the effects of Cu and fecal egg count in grazing beef cows (n = 40). Cows were blocked by parity and body weight (BW) then randomly assigned to 1 of 2 treatments: standard offering of copper via free choice mineral (CON; Ragland Sweet Mag Mineral Mix, 425 ppm Cu) and those receiving a 25 mg Cu rumen bolus in addition to the standard offering (Santa Cruz Animal Health, Dallas, TX). Cattle were managed as a single herd at the with equal access to water, a grain supplement, and a warm season grass pasture. Fecal samples via rectal grab, blood via coccygeal venipuncture, BW, BCS, hair coat (1 being the healthiest) and shedding (1 being the most slick) scores were all collected on d 0, 10, 24, 38, and 66 relative to treatment initiation. Sera were analyzed to determine circulating Cu, macrominerals, urea, creatinine, and various blood proteins. Fecal egg counts were conducted to determine Coccidial, Moniezia, and Trichostrongyle egg content. Data were analyzed using the GLIMMIX procedure of SAS 9.4 (SAS inst. Inc, Cary, NC). No treatment × day interaction (P = 0.988) was observed for circulating Cu; however, Cu decreased (P < 0.001) in all cattle over time, and TRT tended (P = 0.090) to have increased Cu compared with CON. No interactions or main effects occurred (P > 0.509) for BW. No interaction (P = 0.4389) occurred for BCS, hair, or shedding scores. Hair scores (P < 0.001), shedding scores (P < 0.041), and BCS(P < 0.001) decreased in all cattle over time. Body condition for TRT (5.2 ± 0.056) was greater (P =.0024) than CON (4.9 ± 0.057). Hair score by day decreased (P < 0.001) in TRT, while the shedding had a tendency of increasing (P = 0.0411) by TRT. There were no interactions or main effects on Coccidial (P < 0.220) or Trichostrongyle (P < 0.274) egg content. While no interaction (P = 0.673) for Moniezia was observed, TRT tended (P = 0.095) to have fewer Moniezia eggsthan CON. No interactions (P > 0.100) were observed for any of the blood metabolites, and while they differed (P < 0.05) day to day for all cows, no treatment effects occurred (P > 0.10). Although Cu bolus administration at this concentration did tend to change Cu copper in the animal, effects resulting from it were minimal.