The Impact of Oregano Essential Oil and the Finishing System on Performance, Carcass Characteristics and Meat Quality in Heifers

The aim of this study was to evaluate the effects of oregano essential oil (OEO) as a replacement for monensin (MON) on performance, carcass characteristics and meat quality in heifers finished either in confinement or on pasture. Thirty-six Nellore heifers (252.44 kg ± 21.80 kg) were distributed in a completely randomised design in a 2 × 2 factorial scheme, with two types of additives and two finishing systems. In both systems, a concentrate at 1.5% of body weight (BW) on a dry matter (DM) basis containing MON (282.2 mg/animal/day) or OEO (300 mg/animal/day) was offered daily. The final BW (FBW) and average daily gain (ADG) were higher in confinement-finished animals than in those finished on pasture (p < 0.01). There was no effect from the finishing system (p ≥ 0.376) or additive (p ≥ 0.057) for hot-carcass weight, hot-carcass yield, subcutaneous fat thickness, or the Longissimus lumborum area. The pH and shear force of the meat did not differ between treatments (p ≥ 0.076). Finishing in confinement resulted in brighter meat than finishing on pasture (p ≤ 0.006). The use of OEO increased the redness of the meat (p ≤ 0.042). Consumer perception (n = 63) of the sensory attributes of aroma, colour, tenderness, flavour and juiciness was not affected by the treatments (p > 0.05). Heifers finished in confinement or on pasture, with the same proportion of concentrate in the diet and the addition of MON or OEO, presented similar characteristics for both the carcass and the meat.