PSIX-15 The Influence of Trace Mineral Source on Reproductive Performance in Recipient Multiparous Beef Cows

Fifty cow-calf pairs were used to investigate the influence of trace mineral (TM) source on reproductive performance following embryo transfer. Cows were blocked by BW and breed and sorted into pens containing 5 cow-calf pairs. Each group was randomly assigned to one of the following treatments: 1) Organic TM (OTM): 75 mg of Cu from Cu proteinate, 8 mg of Co from Co proteinate, 105 mg of Mn from Mn proteinate, 3 mg of Se from Sel-Plex, and 220 mg of Zn from Zn proteinate, animal-1∙d-1; and 2) Inorganic TM (ITM): 255 mg of Cu from Cu sulfate, 2.6 mg of Co from Co carbonate, 1018 mg of Mn from Mn sulfate, 3 mg Se from sodium selenate, and 763 mg of Zn from Zn sulfate, animal-1∙d-1. All cows were fed a roughage-based diet with no supplemental Cu, Co, Mn, Se, or Zn. Cows were individually fed 0.9 kg of the appropriate supplement pellets daily to deliver TM treatments for 89-d, starting 5-d after estrous synchronization. Estrous was synchronized in all cows on d 0 of the experiment and cows received embryos 8-d after expressing estrous. Serum and plasma were obtained every 28-d and analyzed for reproductive hormones and TM, respectively. Data were analyzed as a randomized block design in R (version 4.0.5). Reproductive performance and hormone concentrations were similar across treatments. Cows receiving OTM had greater Se (P < 0.05) and Cu (P < 0.05) concentrations when compared to ITM. There was a treatment x time interaction for Cu concentrations (P < 0.03). Copper concentrations decreased over time in ITM supplemented cows and increased over time in OTM supplemented cows. These data suggest that TM source did not impact reproductive performance but did improve Cu and Se status in cows over the 94-d experiment.