Research Summary - 4
Reduced feed efficiency, pathologic cardiopulmonary remodeling, and increased mortality in feedyard cattle with underlying pulmonary hypertension
| Date/Time: |
9/13/2025
14:00
|
| Author: |
Greta M Krafsur |
| Clinic: |
University of Nebraska-Great Plains Veterinary Educational Center |
| City, State, ZIP: |
Clay Center, NE 68933 |
G.M. Krafsur, DVM, DACVP, MSc, PhD Candidate
1
;
M.M. Culbertson, PhD
2
;
R.D. Brown, PhD
1
;
T.N. Holt, DVM
3
;
R.M. Enns, PhD
4
;
R.A. Bowen, DVM, PhD
5
;
K.R. Stenmark, MD
1
;
M.G. Thomas (deceased), PhD
6
;
1Department of Pediatrics, Critical Care Medicine, Cardiovascular Pulmonary Research Laboratories, University of Colorado-Denver Anschutz School of Medicine, Aurora, CO 80045
2Department of Animal Sciences, Iowa State University, Ames, IA 50111
3Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523
4Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523
5Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
6Texas A&M AgriLife Research, Beeville, TX 78102
Introduction:
Heart failure (HF) increasingly impacts animal health, performance, and profitability in moderate elevation feedlots. Pulmonary hypertension (PH) induced by hypoxic environment is a risk factor for right heart failure (RHF) and death in cattle at high elevation. We hypothesized that a subset of susceptible altitude-naïve cattle would exhibit pre-existing or early-onset PH and pathologic cardiopulmonary remodeling, reduced feedlot performance characteristics, and increased mortality during fattening at moderate elevation.
Materials and methods:
Post-weaning Angus steers (n = 107) from a moderate elevation (1250 m) cow-calf operation with a history of feedlot HF were monitored through a standard fattening cycle (target gain, 1.5 kg/day for 9 months). Pulmonary arterial pressures (PAP) were measured at 3, 6, and 9 months on feed. Divergent low (LPAP) and high (HPAP) phenotypes were observed by 3 months of feeding with progressively worsening PH in HPAP animals. Steers identified as HPAP (n = 23) or LPAP (n = 22) after 6 months on feed were placed in a feed intake evaluation system for the final 60 days of finishing to determine feed performance. Mean PAP at 9 months in the LPAP and HPAP groups were 43.9 +/- 2.5 and 85.4 +/- 21.3 mm Hg (P = 0.015), respectively. Postmortem evaluations of cardiopulmonary morphology and histopathology and carcass traits were performed at harvest.
Results:
High PAP animals showed pulmonary vascular remodeling consistent with PH, right ventricular hypertrophy (RVH, 0.37 kg larger; P < 0.001), and elevated morphologic heart scores, a metric of cardiac remodeling (P < 0.05). Final body weight (595.8 +/- 14.0 kg) and carcass traits were similar among the two groups. However, HPAP steers had reduced average daily gain (0.98 ± 0.20 vs. 1.25 +/- 0.10 kg/d, P=0.04) and feed efficiency (feed:gain, 3.85 +/-0.32 vs. 2.8 +/- 0.12 kg/kg, P=0.005) during the last 60 days of feeding relative to the LPAP steers. Death loss occurred exclusively in HPAP animals >6 months on feed (n=5, 4.8%) and was associated with clinical symptoms and postmortem evidence of HF.
Significance:
This study showed that a subset of PH susceptible animals with reduced feed efficiency, worsened cardiopulmonary remodeling, and increased mortality is present among altitude-naïve beef cattle during fattening at moderate elevation. Undetected PH may underlie the increased incidence of HF and adverse health outcomes under current feeding practices.
