Beta-agonist administration in cattle increases lean muscle mass and body weight through activation of adrenergic pathways.

Study: Effect of beta-agonist type and timing of Experior feeding on calculated cumulative ammonia gas emissions, live growth performance, and carcass outcomes, and objective tenderness outcomes of feedlot steers

Giving cattle a specific drug called Experior made them grow bigger muscles and heavier carcasses, exactly as the claim says. The drug works by stimulating natural body pathways that build muscle.

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

Giving cattle these specific drugs made them grow bigger muscles and gain more weight without eating more food, which is exactly what the claim says happens when beta-agonists are used.

Study: The Beta-adrenergic agonist, Ractopamine, increases skeletal muscle expression of Asparagine Synthetase as part of an integrated stress response gene program

This study shows that giving cattle a beta-agonist drug turns on genes that help build more muscle protein, which explains why these drugs make animals leaner and heavier. It doesn’t measure weight directly, but it shows exactly how the drug works inside the muscle.

Study: The impact of copper status on lubabegron fumarate-induced growth and adipose immune cell infiltration in beef feedlot steers

Giving cattle a specific drug (lubabegron) made them grow more muscle and gain more weight, just like the claim says. The drug works by stimulating natural body pathways that help turn food into muscle instead of fat.