Effects of garlic and rosemary essential oils on growth performance, carcass traits, and meat quality of lambs fed high-concentrate diets

The use of essential oils (EOs) as natural feed additives has been proposed to improve ruminal fermentation and productive performance in small ruminants. This study evaluated the effects of dietary supplementation with garlic (Allium sativum) and rosemary (Rosmarinus officinalis) essential oils at different concentrations on growth performance, carcass traits, and meat quality of lambs fed high-concentrate diets. Thirty-five crossbred lambs were assigned to five treatments: Control, Garlic high (216 mg/kg DM), Garlic low (30 mg/kg DM), Rosemary high (216 mg/kg DM), and Rosemary low (86 mg/kg DM). Rosemary low increased average daily gain (0.193 vs 0.132 kg/day; P < 0.01) and improved feed conversion ratio (6.75 vs 11.07; P = 0.04) compared with the control treatment. In addition, lambs fed Rosemary low showed greater dry matter intake during the later feeding periods. Average daily gain decreased linearly over time, whereas dry matter intake showed a treatment × period interaction. Garlic essential oil supplementation did not differ from the control treatment for growth performance variables. Rosemary low also increased final body weight and carcass weights without affecting carcass yield. Meat pH, color, and lipid oxidation were not affected by dietary treatments. In conclusion, rosemary essential oil at low dosage improved growth performance and feed efficiency without compromising meat quality, supporting its use as a natural additive in intensive lamb finishing systems.