Date of Graduation

12-2025

Document Type

Thesis

Degree Name

Master of Science in Animal Science (MS)

Degree Level

Graduate

Department

Animal Science

Advisor/Mentor

Rivera, Daniel

Committee Member

Powell, Jeremy

Second Committee Member

Justice, Maggie

Keywords

beef calves; calf performance; injectable trace minerals; stress

Abstract

One hundred and fourteen calves (average BW= 224kg ± 89kg) were utilized to evaluate the effects of injectable trace mineral (ITM) administration on calf performance and health when administered pre-weaning and at weaning. Calves were blocked by sex, stratified by age, and randomly assigned to one of the following treatment groups: 1) no ITM injection (CON), 2) ITM administered 28 d before weaning (PW), or 3) ITM administration at weaning (WEAN). Calves were vaccinated against respiratory pathogens on D-28 and D0. At weaning, cattle were transported to a local auction market, held overnight and returned the following morning. Body weight (BW) and blood samples were collected on D-28, D1, D7, D21 and D42 to evaluate haptoglobin, antibody titers (bovine respiratory syncytial virus; BRSV), and serum minerals (Co, Cu, Fe, Mn, Mo, Se, and Zn). Hair cortisol was collected on D0 and D42 to assess chronic stress. Data were analyzed using PROC MIXED of SAS 9.4 with significance declared at P ≤ 0.05 and tendencies at 0.05 < P ≤ 0.15. Serum Se increased in PW calves following ITM administration (P = 0.0013). Serum Mn increased over time in both PW and WEAN groups (P = 0.0003), and PW calves had greater Cu at weaning (P = 0.0163). A sex effect was observed for Zn (P = 0.0119). Heifers tended to have greater Zn serum when sex × time (P = 0.0552) and sex × treatment (P = 0.0828) interactions were evaluated. No treatment differences were observed for BRSV titers (P = 0.6624), haptoglobin (P = 0.9935), or hair cortisol (P = 0.2012). Time effects were observed for haptoglobin and hair cortisol concentrations (P < 0.0001), and BRSV titers (P = 0.1252). No treatment differences were observed in BW at pre-weaning (P = 0.9447), weaning (P = 0.9439), D21 (P = 0.9694), and D42 (P = 0.921). However, a tendency for WEAN calves to have greater DMI was observed (P = 0.1471). Timing of ITM administration did not affect performance, stress, or biomarkers in weaned calves; overall, ITM had no impact under this study’s conditions, with well managed calves. Effects of Injectable Trace Mineral Timing on Calf Performance and Health Indicators

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