Effect of ascorbic and folic acids supplementation on oxidative hormones, enzymatic antioxidants and blood properties of laying hens exposed to increased heat load in a hot humid environment

An experiment was conducted on the effect of supplementation of ascorbic and folic acids on the oxidative hormones, enzymatic antioxidants, haematological and biochemical properties of layers exposed to increased heat load. A total of 72 Isa Brown laying hens at 31 weeks of age were randomly divided into four groups of 18 birds sub-divided into three replicates and indicated as T1, T2, T3 and T4. The birds, housed in deep litter system, were subjected to 3-hours additional heat generated with a kerosene stove for four consecutive days of each week for 12 weeks. The diets for T2, T3 and T4 were supplemented with 250mg of ascorbic acid, 250mg of ascorbic acid + 1mg of folic acid and 300mg ascorbic acid + 1mg of folic acid per kg of feed, respectively. T1 served as the control group. The results showed that T3 and T4 had the lowest concentrations of oxidative hormones which differed significantly (P<0.05) with T1. The enzymatic antioxidants were significantly higher in the supplemented groups than in the control group. Red Blood Cell count differed significantly (P<0.05) between treatments with T4 having the highest RBC counts (1.83x106/mm3). The haemoglobin concentration was significantly different (P<0.05) between the treatments with T4 having the highest haemoglobin value (8.46g/dl). Total protein, globulin and albumin recorded the highest (P<0.05) concentrations in T4 (70.97mg/dl), (65.44mg/dl) and (3.29mg/dl) respectively. Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) recorded the highest (P<0.05) values in the control group T1. These results suggest that dietary inclusion of ascorbic at 300mg/kg and folic acid at 1mg/kg feed reduced the concentration of oxidative hormones, increased red blood cell and haemoglobin concentration and influenced the production of enzymatic antioxidants and is therefore recommended in feeding layers under hot environments.Keywords: Layers, increased heat load, ascorbic and folic acid