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Session: Physiology and Endocrinology I: Metabolism, Endocrine, and/or Stress Interactions

277 - Live Animal Mitochondrial Markers During the Feedlot Phase Are Related to Meat Quality in Angus but Not Brahman Steers

Monday, June 27, 2022

11:00 AM – 11:15 AM CT

Location: Oklahoma City Convention Center, 207 A/B

Presenting Author(s)

PS

Pier L. Semanchik, n/a

Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research
College Station, Texas

Author(s)

LW

Lauren T. Wesolowski

Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research
College Station, Texas
JS

Jessica L. Simons, n/a

Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research
College Station, Texas
Chloey Guy, MS

Research Assistant
Texas A&M AgriLife Research Center, Overton
Overton, Texas
Audrey L. Earnhardt, MS

Graduate Student
Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research; Texas A&M AgriLife Research and Extension Center Overton
College Station, Texas
GP

George A. Perry, n/a

Associate Professor
Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research; Texas A&M AgriLife Research and Extension Center Overton
Overton, Texas
CL

Charles R. Long, Ph.D.

Resident Director
Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research; Texas A&M AgriLife Research and Extension Center Overton
Overton, Texas
DL

Dustin Law

Texas A&M AgriLife Research Overton
Overton, Texas
DN

Don A. Neuendorff, M.S.

Research Associate
Texas A&M AgriLife Research Overton
Overton, Texas
RR

Ron D. Randel, Ph.D.

Professor
Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research; Texas A&M AgriLife Research and Extension Center Overton
Overton, Texas
TM

Tanner Machado

Texas A&M University, Kingsville
Kingsville, Texas
TW

Thomas H. Welsh, Jr.

Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research
College Station, Texas
Sarah H. White-Springer, PhD

Assistant Professor
Department of Animal Science, Texas A&M University; Texas A&M AgriLife Research
College Station, Texas

Abstract: Mitochondrial activity correlates with meat product quality post-harvest but little is known about the relationships between live animal mitochondria and product quality at slaughter. To test the hypothesis that live animal skeletal muscle mitochondrial markers would be correlated with longissimus Warner-Bratzler shear force (WBSF) post-harvest, longissimus thoracis (LT) and trapezius (TRAP) samples were collected from Brahman and Angus steers (n = 36 per breed) during the grazing growth phase (GP) and after 120 days on feed (FP). Samples were analyzed for mitochondrial enzyme activities via colorimetry and for oxidative phosphorylation (P) and electron transfer (E) capacities via high-resolution respirometry. Relationships between mitochondrial variables and WBSF were determined using PROC CORR in SAS (v9.4). Within Angus in GP, LT mitochondrial volume density as measured by citrate synthase activity (CS) was positively correlated with WBSF (P=0.009). In FP, Angus LT intrinsic (relative to CS) P with complex I (P_CI) and maximal E with complexes I and II (E_CI+II) were positively correlated with WBSF (P≤0.05), while the contribution of maximal P with complexes I and II (P_CI+II) to maximal E (flux control ratio, FCR_PCI+II) was negatively correlated with WBSF (P=0.03). Also in FP, Angus TRAP integrative (relative to mg tissue) P<sub>CI, P<sub>CI+II, and E_CI+II and FCR_PCI were negatively correlated with WBSF (P≤0.02), while the FCR for electron transfer through complex II only (FCR_ECII) was positively correlated with WBSF (P=0.007). In Brahman, no mitochondrial markers correlated with WBSF during either GP or FP. Post-harvest meat tenderness is related to live animal skeletal muscle mitochondrial markers when evaluated close to slaughter in Angus but not in Brahman steers.