Effects of Different Dietary Energy Levels on Development, Quality of Carcass and Meat, and Fatty Acid Profile in Male Lambs

SIMPLE SUMMARY: Alpine Merino sheep are a new breed of sheep adapted to the cold and arid ecological zone 2400–4070 m above sea level; the breed has important economic significance for high-altitude areas. This study evaluated the effects of different dietary energy levels (9.7 MJ/kg, 10.1 MJ/kg, 10.5 MJ/kg) on the growth and meat quality of weaned Alpine Merino lambs. The results showed that compared with the low-energy diet (9.7 MJ/kg), the high-energy (10.5 MJ/kg) diet promoted the growth and development of lambs, increased the live weight and carcass weight of lambs before slaughter, significantly reduced the yellowness and redness scores of lamb muscles, and increased the meat’s content of monounsaturated fatty acids. ABSTRACT: This experiment was conducted to study the effects of dietary energy level on the growth performance and meat quality of weaned Alpine Merino lambs. The study ran for a total of 104 days (20-day pretrial, 84-day trial). From three groups of test lambs, we randomly selected ten lambs per group to determine slaughter performance, meat quality characteristics, and organ indexes. The slaughter performances of the lambs improved as the dietary energy level increased. The live weight before the slaughter of the lambs was significantly higher in the high group than in the low and medium groups. The carcass weight was significantly higher in the high group than in the low group. Dietary energy level had little effect on the organ weight of lambs. Meat quality differed among the three dietary energy levels. The muscle yellowness and redness scores decreased significantly as the energy levels increased. The C18:0, C21:0, C20:1, C18:2n6c, and C20:2 contents in the muscle were significantly higher in the high group than in the medium and low groups. The C18:3n6 content in the muscle was significantly higher in the low group than in the medium group. The C20:5n3 content in the longissimus dorsi was significantly higher in the high group than in the medium and low groups. The monounsaturated and unsaturated fatty acid contents in the muscle were significantly higher in the high group than in the low group. A dietary energy level of 10.5 MJ/kg is suitable for fattening weaned male Alpine Merino lambs.