Meat Quality of USDA Choice Holstein Steers Supplemented with Lubabegron

Abstract The mitigation of ammonia emissions in cattle production systems has led to a growing interest in alternative feeding strategies that maintain feed efficiency and enhance environmental sustainability. Lubabegron (LUB), a novel β-agonist, has shown promise in reducing ammonia release in cattle, prompting investigation into its broader effects on meat quality. This study evaluated the impact of lubabegron supplementation on sensory attributes, fatty acid profiles, and protein degradation in Longissimus lumborum (LL) muscle of Holstein steers. Beef strip loins (n=212) were collected from Holstein steers supplemented with lubabegron at a dosage of 3.2g/ton for 28 (LUB28), 56 (LUB56), or 84 (LUB84) days prior to slaughter, were compared with control (CON) steers which were not fed LUB. Striploins were cut into 2.54 cm steaks and aged for 7, 14, 21, 28, or 35 days. A subsample of steaks (n= 240) were then randomly assigned to trained sensory evaluation and an additional subsample of steaks (n=200) were evaluated for fatty acid composition and protein degradation. Trained sensory panels assessed tenderness, flavor, and texture attributes, revealing a decrease in tenderness scores with lubabegron supplementation (P=0.02). However, when steaks were evaluated based on aging duration, regardless of LUB supplementation, it was found that steaks aged for 28 d or longer became were more tender (P=0.03). Additionally, the duration of aging affected the intensity of off-flavor notes, oxidized, liver-like, and sour, became more pronounced in steaks aged for 35 d (P<0.01). Fatty acid analysis indicated significant variations in specific saturated and polyunsaturated fatty acids, notably increasing at 56 days of supplementation. Additionally, total concentration for PUFA displayed interesting results, indicating that concentration levels were the highest for cattle fed LUB for 56 d (P=0.02). Contradictory findings in previous literature regarding the impact of β-agonists on fatty acid profiles underscore the need for further investigation. Protein degradation analysis revealed enhanced desmin integrity with lubabegron supplementation, particularly notable at the 28-day aging mark specifically, for cattle fed LUB for 56 d (P<0.01). While some studies have correlated degraded desmin with increased tenderness, the exact implications of lubabegron on protein degradation warrant further exploration for a comprehensive understanding of its effects on beef quality. These findings suggest that lubabegron supplementation influences various aspects of beef quality, with implications for consumer acceptability. Further research is necessary to fully comprehend the mechanisms underlying these effects.