Effects of combining immunocastration and β-adrenergic agonists on the meat quality of Nellore cattle

Abstract The effects of immunocastration in combination with β-adrenergic agonists (β-AA) on meat quality traits were evaluated. A randomized complete block design with a 2 × 3 factorial arrangement (gender [NoC, non-castrated; ImC, immunocastrated] x diet [CO, without β-AA; ZH, 80 mg/animal/day of zilpaterol hydrochloride; RH, 300 mg/animal/day of ractopamine hydrochloride]) was used, and 96 animals and 16 replications were evaluated per treatment. One-half of the animals were immunocastrated (ImC, n  = 48), while the other 50% remained intact (NoC, n  = 48). The β-AA treatments were administered for 30 d prior to slaughter. Instrumental meat quality, dark cutting percentage, expression of genes encoding proteolytic enzymes, and consumer sensory panel ratings were evaluated in the Longissimus thoracis muscle. Compared to the NoC animal meat, the ImC animal meat had a greater shear force, lesser dark cutting percentage, and poorer overall liking and tenderness ratings as assessed by the consumer sensory panel ( P  ≤ 0.05). Feeding β-AA increased the shear force and resulted in the worst overall liking and sensory tenderness ratings. The ImC decreases the tenderness of fresh meat and negatively affects the overall liking and tenderness sensory ratings. The β-AA negatively affects the overall liking and sensory tenderness. The ZH has a more pronounced effect on reducing objective tenderness than RH.