Effects of lubabegron dose and duration on calculated cumulative ammonia gas emissions and growth performance by feedlot steers during the last 28, 56, or 84 days of the feeding period

• Published in: Applied Animal Science 2024-10, Vol.40 (5), p.669-680
• Main Authors: Edmonds, Matt, Kube, John C., Allen, Janet B., Calvo-Lorenzo, Michelle, McKenna, David, Woerner, Dale, Nair, Mahesh, Corona, Ashley, Scanga, John, Rincker, Phil, Camara, K., Brown, M.S.
• Format: Article
• Language: English
• Subjects: ammonia; beta-adrenergic modulator; growth; lubabegron; mobility
• ISSN: 2590-2865
• DOI: 10.15232/aas.2023-02518

Our objective was to characterize the effects of lubabegron (Experior 10; Elanco Animal Health, Greenfield, IN) on ammonia gas emissions, growth and carcass merit, and animal mobility of feedlot steers. Crossbred beef steers were used in a randomized complete block with a 4 × 3 factorial arrangement of dietary lubabegron concentrations. (LUB; 0, 1.5, 3.5, or 5.5 mg/kg of DM) and duration of feeding (28, 56, or 84 d before slaughter). Blocks were slaughtered after an equal time on feed. Calculated cumulative ammonia gas emissions per kilogram of hot carcass weight decreased after 28 d (linear) as LUB increased and responded quadratically after 56 and 84 d (LUB × duration). Steer DMI (LUB × duration) decreased linearly as LUB increased after 28 and 56 d. Final shrunk BW and ADG (LUB × duration) increased (linear) as duration increased and increased (quadratic) as LUB increased. The increase in G:F (LUB × duration) as LUB increased was linear within each duration, with an increasingly smaller magnitude as duration increased. Steer G:F increased linearly as duration increased when 0, 1.5, and 3.5 mg/kg of DM was fed. Steer DP (LUB × duration) increased quadratically as duration increased and linearly as LUB increased. Marbling score (LUB × duration) decreased quadratically as LUB increased when fed for 84 d and decreased linearly when 1.5 or 3.5 mg/kg of DM was fed. Average YG decreased (LUB × duration) linearly as LUB increased. Neither LUB nor duration altered the distribution of mobility scores at lairage before slaughter. Feeding lubabegron resulted in lesser calculated ammonia emissions per kilogram of output, ≤0.3 kg/d lesser DMI, up to 19 kg more hot carcass weight, and leaner carcasses with a lesser marbling score after 56 d and did not alter health status or animal mobility after transport to slaughter.