Melatonin improves growth and slaughter performance of broilers by regulating satellite cell proliferation via RORα nuclear receptor

To investigate the molecular mechanisms of melatonin on the growth and slaughter performance of broilers, 144 newly hatched male broilers were randomly assigned to dietary melatonin (0, 5, 20, or 80 mg/kg) for 42 days. Chicken skeletal muscle satellite cells (SMSCs) were treated with melatonin (0.5–312.5 ng/mL), and retinoid-related orphan receptor-alpha (RORα) involvement was investigated using agonist SR1078 or inverse agonist SR3335. Growth and slaughter performance, serum antioxidant capacity, meat quality, as well as molecular expression levels analyzed for skeletal muscle growth related factor were conducted. The results demonstrated dietary melatonin significantly decreased feed gain ratio, and elevated muscle percentage (P < 0.05), serum melatonin content (P < 0.05), total antioxidation capability (T-AOC) and the activity of antioxidant enzymes (P < 0.05), while reduced the levels of malondialdehyde (MDA) (P < 0.05). Administration of melatonin notably improved the water-holding capacity and myofiber area of muscles (P < 0.05). Additionally, melatonin significantly upregulated the expression of paired domain homeobox transcription factor 7 (Pax7), myoblast determination protein (MyoD), and myogenic factor 5 (Myf5) in muscles and SMSCs, downregulated Myostatin (MSTN) (P < 0.05). In the presence of melatonin, the SR1078 markedly enhanced Pax7 expression, while the SR3335 reduced the expression of Pax7, MyoD, and Myf5 (P < 0.05). In conclusion, melatonin has the potential to regulate the proliferation of chicken SMSCs through the RORα nuclear receptor, affecting the expression levels of skeletal muscle growth related factor in SMSCs, promoting the growth and slaughter performance of broilers.