Animals (Sep 2021)

Initial Liver Copper Status in Finishing Beef Steers Fed Three Dietary Concentrations of Copper Affects Beta Agonist Performance, Carcass Characteristics, Lipolysis Response, and Muscle Inflammation Markers

  • Elizabeth Messersmith,
  • Mark Branine,
  • Olivia Genther-Schroeder,
  • Jodi McGill,
  • Stephanie Hansen

DOI
https://doi.org/10.3390/ani11092753
Journal volume & issue
Vol. 11, no. 9
p. 2753

Abstract

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Ninety-three Angus-crossbred steers (470 ± 35 kg) were assigned to a 3 × 2 factorial to determine the effects of Cu status and beta agonist (BA) on performance, carcass characteristics, lipolytic rate, and muscle inflammation. Factors included Cu supplementation (mg Cu/kg dry matter (DM)) at: 0 (LO), 10 (MED), or 20 (HI) from Cu amino acid complex (Availa Cu; Zinpro) with no BA (NoRAC) or 300 mg·steer−1·day−1 of ractopamine hydrochloride (RAC; Optaflexx; Elanco) for final 28 days of 88-day trial. Linear and quadratic effects of Cu status within BA treatment were tested. Pre-BA gain was not affected by Cu supplementation (p ≥ 0.57), although day 53 liver Cu quadratically increased (p = 0.01). Average daily gain and muscle IL-8 gene expression quadratically increased (p ≤ 0.01), with MED having greatest gain and gene expression. Ribeye area tended to quadratically increase with Cu supplementation within RAC (p = 0.08). In vitro basal lipolytic rate tended to quadratically increase with Cu supplementation within RAC (p = 0.11), while stimulated lipolytic rate tended to linearly increase within NoRAC (p = 0.10). These data suggest lipolysis and the BA response of steers are influenced by dietary and liver Cu concentrations.

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