@article{mmb 14456, author = {Katherine G. Hochmuth, Matthew D. Schulte, Elizabeth M. Messersmith, Elisabeth J. Huff-Lonergan, Stephanie L. Hansen}, title = {The Influence of Supplemental Zinc and Ractopamine Hydrochloride on the Performance and Longissimus Thoracis Proteome of Finishing Beef Steers}, volume = {6}, year = {2022}, url = {https://www.iastatedigitalpress.com/mmb/article/id/14456/}, issue = {1}, doi = {10.22175/mmb.14456}, abstract = {To determine how Zn and ractopamine hydrochloride (RAC) supplementation affect the <i>longissimus thoracis</i> muscle proteome in beef cattle, 48 high percentage Angus steers (494±18.2 kg) were utilized in a 2×2 factorial study design. Steers were blocked by body weight (BW) and genetic gain potential (GeneMax; Zoetis, Parsippany, NJ) into control (CON; analyzed 36 mg Zn/kg dry matter [DM]) or supranutritional Zn (SUPZN; CON+60 mg Zn/kg DM from ZnSO<sub>4</sub>+60 mg Zn/kg DM from Zn-amino acid complex; Availa Zn, Zinpro, Eden Prairie, MN) dietary treatments (ZNTRT). Starting 28 d prior to harvest, steers were blocked by BW within ZNTRT to RAC treatments (RACTRT) of 0 (NO) or 300 mg·steer<sup>−1</sup>·d<sup>−1</sup> (RAC; Actogain 45, Zoetis). After 15 d on RACTRT, <i>longissimus thoracis</i> biopsies were collected from all steers for proteomic analysis. Twenty-eight steers (<i>n</i>=7 per treatment) were harvested at a commercial abattoir on Day 90. A ZNTRT×RACTRT effect showed SUPZN-RAC steers had a greater dressing percentage than other treatments (<i>P</i>≤0.02). Steers fed SUPZN had a greater hot carcass weight, carcass-adjusted final BW, overall average daily gain, and overall gain to feed (<i>P</i>≤0.05). Differentially abundant proteins involved in energy metabolism, muscle structure, and protein synthesis potentially indicate muscle fiber characteristic differences because of Zn and RAC supplementation.Both myosin light chain kinase 2 and eukaryotic translation initiation factor 5A-1 were more abundant in SUPZN-RAC steers than SUPZN-NO (<i>P</i>≤0.05) or CON-NO (<i>P</i>≤0.04) steers when analyzed for phosphorylation modifications. L-lactate dehydrogenase B was more abundant in SUPZN-NO steers than CON-NO (<i>P</i>=0.03) or CON-RAC (<i>P</i>=0.01) steers. In conclusion, increased Zn supplementation may be needed to optimize the hypertrophic effects of RAC through its effects on the <i>longissimus thoracis</i> proteome.}, month = {11}, pages = {1–17}, keywords = {beef cattle,beta adrenergic agonists,muscle,proteomics,zinc}, issn = {2575-985X}, publisher={Iowa State University Digital Press}, journal = {Meat and Muscle Biology} }