The Study
The supplementation of lubabegron or ractopamine hydrochloride in the summer improved growth performance but did not impact rumination, mobility scores, and behaviors in feedlot cattle in the United States
This study is like a fair test where cows were randomly given different snacks to see which made them grow bigger and fitter. It found that two special snacks helped cows grow better, but didn't make them sicker or change how they acted. But it doesn't prove the snacks are safe for all cows or in all weather.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists gave two different supplements to beef cattle for 35 days before slaughter to see if they grew bigger and leaner without acting strangely or getting sick.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 520 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means farmers can make more lean beef from the same amount of feed without harming the animals' health or comfort during hot weather.
- 2Cattle given the supplements gained 12–15% more weight per day, used feed 8–10% better, had 8–10% heavier carcasses, and 10–12% bigger muscle areas — but ate the same amount, moved normally, and behaved the same as cattle without supplements.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Animal Science
Year
2026
Authors
H. Loh, Paxton Sullivan, Jeniffer Backes-Kincher, M. Calvo-Lorenzo, T. E. Engle, L. Edwards-Callaway
Related Content
Claims (6)
Administering beta-agonists to cattle results in increased lean muscle mass and higher body weight by stimulating adrenergic pathways.
Feeding feedlot steers ractopamine hydrochloride or lubabegron for 35 days increases hot carcass weight by 8–10% and longissimus muscle area by 10–12% compared to steers not fed these supplements, with no change in dressing percentage, marbling, fat depth, or meat color.
Feeding feedlot steers ractopamine hydrochloride or lubabegron for 35 days during summer does not change reticulorumen pH, temperature, or rumination time, indicating no impact on rumen fermentation or metabolic heat production under mild heat stress.
Feeding ractopamine hydrochloride or lubabegron to cattle during the last 35 days before slaughter increases their daily weight gain by 12-15% and improves how efficiently they convert feed into body mass, leading to heavier animals with more lean muscle, without changing how much feed they consume.
When feedlot steers are given ractopamine hydrochloride or lubabegron for 35 days during summer, their mobility scores do not change significantly, and at least 89% of all cattle maintain normal gait regardless of treatment.
When feedlot steers are given ractopamine hydrochloride or lubabegron daily for 35 days in summer, their feeding, drinking, standing, and lying behaviors change temporarily and vary by time of day and week, but no consistent pattern emerges that differs between the two treatments.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.