Effects of dietary α-lipoic acid, acetyl-L-carnitine, and sex on antioxidative ability, energy, and lipid metabolism in broilers

An experiment was conducted to evaluate the effects of dietary alpha-lipoic acid (LA), acetyl-L-carnitine (ALC), and sex on antioxidative ability, energy, and lipid metabolism in broilers. A total of 972 one-day-old broilers with equal sex were randomly assigned in a 3 x 3 x 2 factorial design using 3 LA, 3 ALC levels, and 2 sexes (6 replications, 9 birds/replication). The LA and ALC levels were 0, 50, and 100 mg/kg, respectively. Results showed that increased LA or ALC resulted in increased total antioxidant capacity and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and decreased levels of malondialdehyde in serum and liver of birds (P < 0.05). In addition, with increasing addition of LA or ALC, an increased (P < 0.01) level of insulin (Ins), as well as decreased (P < 0.05) levels of glucose and glucagon (Glu), were observed in serum of broilers. Total cholesterol and triglyceride (TG) levels decreased (P < 0.05) and nonesterified fatty acid, lipoprotein lipase, and lipase levels increased (P < 0.05) in serum with increased administration of LA or ALC. Moreover, a significant (P < 0.05) interaction of LA x ALC was observed for serum and liver SoD, serum GSH-Px, glucose, and TG levels. Birds fed diets containing 50 mg/kg of LA and 50 mg/kg of ALC had higher serum and liver SoD activities and lower serum glucose and TG levels than those fed diets containing 100 mg/kg of LA or ALC alone. The main effect of sex and all interactions among main effects (except LA x ALC) were not significant (P > 0.05) for all of the above parameters. overall, the present data indicate that LA or ALC supplementation, or both, at low levels (50 or 100 mg/kg) improved antioxidative ability, energy metabolism, and lipid metabolism in broilers, and synergistic effects by the combined supplementation of LA and ALC were indicated by serum and liver SoD activities and serum glucose and TG levels.