Effect of dietary dried oregano leaves supplementation on performance and carcass characteristics of growing lambs

In an experiment with 45 male growing Chios lambs, the effect of dietary dried oregano (Origanum vulgare subsp. hirtum) leaves supplementation on performance and carcass characteristics was determined. In the 10 wk experiment, lambs were allocated to 1 of 3 treatments (OR0, OR144, and OR288) of 15 lambs each. Lambs had an initial body weight (BW) of 17.5 ± 1.8 kg, and were fed a concentrate mixture ad libitum and alfalfa hay at 0.4 kg/(lamb d). The concentrate mixture for treatment OR0 was not supplemented with dried oregano leaves (control), while dried oregano leaves were incorporated into the concentrate mixture of treatments OR144 and OR288 at levels of 4 and 8 kg/t, respectively, to provide oregano essential oil at levels of 144 and 288 mg/kg of concentrate, respectively. No differences were observed among dried oregano leaves inclusion treatments in final BW (36.7 kg), BW gain (BWG, 275 g/d), dry matter intake (DMI, 1.09 kg/d), and feed conversion ratio (3.98 kg DMI/kg BWG). All carcass yield traits as kg/100 kg of BW were unaffected by treatment. Dried oregano leaves supplementation in isonitrogenous and iso (net energy) energetic diets for growing lambs did not affect their performance and carcass characteristics.