**2. Results**

#### *2.1. Lipid Oxidation*

Oregano essential oil (OEO) and monensin (SM) did not have advantages (*p* = 0.28) on the lipid oxidative stability of lamb (Figure 1). However, meat from male lambs fed with a high level of OEO (HO) had a 46% higher (*p* < 0.05) malonaldehyde (MDA) formation (1.15 ± 1.25 mg MDA/kg) when compared to SM (0.79 ± 1.25 mg MDA/kg).

**Figure 1.** Means (± S.E.) of thiobarbituric acid reactive substances (TBARS) values (mg malonaldehyde (MDA)/kg of muscle) in m. *Longissimus lumborum* of male lambs unsupplemented (CON) or supplemented with monensin (SM), or three different levels of oregano essential oils: low (LO = 0.2 g/kg of dry matter (DM)); medium (MO = 0.3 g/kg of DM) or high (HO = 0.4 g/kg of DM). TBARS analysis was performed after 7 d of simulated retail display in modified atmosphere packaging (O2:CO2, 75:25%). a,b Different superscripts mean significant difference (*p* < 0.05) among treatments within the variables.

#### *2.2. Compression Strength*

OEO dietary supplementation reduced the compression force (Figure 2) of lamb (*p* = 0.03). The meat with the medium level of OEO (MO) and the control (CON) meat had the lowest and highest compression strength values, 12.51 ± 1.13 and 17.98 ± 1.32 <sup>N</sup>/cm3, respectively. At day 7, the meat with a high level of OEO (HO) presented the lowest compression strength and the highest oxidation rate. Therefore, a greater PUFA deposition (*p* < 0.05) could be assumed.

**Figure 2.** Means (± S.E.) of compression strength (N/cm3) in m. *Longissimus lumborum* of male lambs unsupplemented (CON) or supplemented with monensin (SM), or three different levels of oregano essential oils (LO = 0.2 g/kg of DM; MO = 0.3 g/kg of DM or HO = 0.4 g/kg of DM). Compression strength analyses were performed after 7 d of simulated retail display in modified atmosphere packaging (O2:CO2, 75:25%). a, b Different superscripts mean significant difference (*p* < 0.05) among treatments within variable.
