Various levels and forms of dietary α-lipoic acid in broiler chickens: Impact on blood biochemistry, stress response, liver enzymes, and antibody titers

The present experiment was conducted to evaluate the impact of various levels and forms of alpha-lipoic acid (ALA) on blood biochemistry, immune and stress response, and antibody titers in broiler chickens. The four levels (7.5, 15, 75, and 150 ppm) and 2 sources (powder, P-ALA and encapsulated, E-ALA) of ALA along with negative (C-) and positive control (C+; contains antibiotics) diets consisted of 10 dietary treatments, and these treatments were allocated to 1,200 1-d-old chicks and were replicated 12 times with 10 birds per replicate. Among the blood biochemistry parameters, creatinine levels were almost 3 times lower in E-ALA-supplemented diets compared to the C- diet (0.09 vs. 0.25 mg/dL; P < 0.0001). Neither level nor source of ALA affected blood urea nitrogen (BUN), total protein (TP), albumin, globulin, or albumin to globulin ratio (AGR). The supplemented diets decreased serum levels of the liver enzymes aspartate-aminotransferase (AST; P < 0.006) and alanine-aminotransferase (ALT; P < 0.0003). The Newcastle disease virus (NDV) antibody response in supplemented groups was poor at day zero (P < 0.0001) but increased by d 14 (P < 0.03). Birds did not respond to infectious bronchitis virus (IBV) vaccination at any observed stage (P > 0.05). The concentration of cortisol was reduced in chickens fed ALA-supplemented diets as compared to the C- diet (P < 0.001). Results suggest that ALA-supplemented diets ameliorated blood biochemistry profiles and immune responses and reduced stress in broiler chickens. The encapsulated form of ALA was more effective than the powder form.