Effects of feeding lubabegron on gas emissions, growth performance, and carcass characteristics of beef cattle housed in small-pen environmentally monitored enclosures during the last 3 mo of the finishing period

We hypothesized that lubabegron fumarate (LUB) (Experior™, Elanco Animal Health, Greenfield, IN), would act as antagonist to ß-adrenergic receptor (ß-AR) subtypes in primary bovine subcutaneous (s.c.) and intramuscular (i.m.) adipocytes differentiated in culture. This study employed LUB, dobutamine (DOB, a selective ß1-agonist), salbutamol (SAL, a selective ß2-agonist), and propranolol (PRO, a non-selective ß-AR antagonist). Preadipocytes were isolated by standard techniques from bovine longissimus muscle and overlying s.c. adipose tissue and differentiated to adipocytes for 14 d. The adipocyte source x stage of differentiation interaction was significant for ß-adrenergic receptors-1 (ADRB1) (P = 0.001) and ADRB2 (P = 0.01) in that expression of ADRB1 and ADRB2 was greater in s.c. adipocytes than in s.c. preadipocytes; expression of the ADRB1-3 did not change after differentiation of i.m. adipocytes. CCATT/enhancer-binding protein alpha (CEBPA) expression increased upon differentiation in both s.c. and i.m. adipocytes (P = 0.006). The source x stage of differentiation interaction was significant for peroxisome proliferator-activated receptor gamma (PPARG) (P = < 0.001) and fatty acid binding protein-4 (FABP4) (P = 0.004). Expression of PPARG increased after differentiation of s.c. preadipocytes to adipocytes, but PPARG expression did not change with differentiation of i.m. preadipocytes to adipocytes. FABP4 expression increased after differentiation of both s.c. and i.m. adipocytes, but FABP4 expression increased to a greater extent in s.c. adipocytes. In s.c. adipocytes, DOB elevated cAMP and glycerol production and protein kinase A (PKA) activity, and SAL increased PKA activity; these effects were abolished by LUB and PRO (P < 0.001). Incubation of i.m. adipocytes with SAL increased cAMP production and PKA activity, which was attenuated by LUB and PRO (P ≤ 0.006). In s.c. adipocytes, SAL, LUB + SAL, and LUB + DOB upregulated hormone sensitive lipase (HSL) (P < 0.001) and perilipin (P = 0.002) gene expression. In i.m. adipocytes, DOB and LUB + DOB increased HSL gene expression (P = 0.001) and LUB + SAL depressed adipose triglyceride lipase expression below control levels (P = 0.001). These results demonstrate that LUB is a ß-AR antagonist at the ß1-AR and ß2-AR subtypes in s.c. adipocytes, and that s.c. and i.m. exhibit different responses to ß-AA and LUB.

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Cattle, carcass, economic, and estimated emission impacts of feeding finishing steers lubabegron or ractopamine hydrochloride

McAtee,

Renter,

Murphy

et al. 2024

Translational Animal Science

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Lubabegron (Experior; Elanco, Greenfield, IN, USA) is the first U.S. Food and Drug Administration approved feed additive for reducing gas emissions from feedlot animals or their waste; it does not have live or carcass performance claims. Our primary objective was to determine the effect of lubabegron on feedlot performance and carcass traits in finishing beef steers compared to ractopamine hydrochloride (Optaflexx; Elanco, Greenfield, IN, USA). A commercial feedlot trial using crossbred beef steers (n = 2,117; 373 ± 15 kg initial body weight [BW]) was completed with a randomized complete block design. Treatments consisted of two feed additives: 1) OPT targeted to deliver 300 mg/animal/d of ractopamine hydrochloride for 28 ± 7 d out from harvest and 2) EXP targeted to deliver 36 mg/animal/d of lubabegron 56 ± 7 d out from harvest and a 4-d pre-slaughter withdrawal period. Twenty 70-142 hd pens with 10 pens per treatment were used. Cattle were weighed at arrival processing and at harvest and fed for an average of 167 days. Data were used to calculate production metrics, partial budgets, and estimated greenhouse gas emissions using published methods, and were analyzed using linear mixed models with pen as the experimental unit and block as a random intercept. A statistical significance threshold of α = 0.05 was determined a priori. There was no evidence for statistically significant differences between treatments for initial BW (P = 0.70), health related outcomes (P values ≥ 0.43), or mobility scores (P = 0.09). Cattle fed EXP had increased final BW, ADG, G:F, and decreased DMI (P values ≤ 0.01) compared to OPT. Carcasses were 11 ± 1.76 kg (HCW) heavier in EXP group (P < 0.01), and differed between treatments for both YG and QG distributions (P values ≤ 0.01). Cattle fed EXP had a shift toward more YG 1 and 2, select and sub-select carcasses compared to OPT, which had as shift toward more YG 3, 4, 5, prime and choice carcasses. With increased beef production and efficiency compared to OPT, the estimated CO2 equivalent emissions from production were reduced 6.2% per unit of carcass weight for EXP (P ≤ 0.01). Estimated net returns/animal shipped were $56.61 ± 9.37 more for EXP than OPT (P ≤ 0.01). In conclusion, when cattle were fed for the same total number of days, feeding EXP compared to OPT increased net returns, feedlot performance, and efficiency, but resulted in carcass yield and quality characteristics that may impact marketing programs.

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Effects of feeding lubabegron on gas emissions, growth performance, and carcass characteristics of beef cattle housed in small-pen environmentally monitored enclosures during the last 3 mo of the finishing period

Cited by 8 publications

References 35 publications

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Lubabegron fumarate acts as a β-adrenergic receptor antagonist in cultured bovine intramuscular and subcutaneous adipocytes

Cattle, carcass, economic, and estimated emission impacts of feeding finishing steers lubabegron or ractopamine hydrochloride

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