Effect of dosage of vitamin E on physiological and blood parameters in growing Arbor acre pullets under humid tropical conditions
One hundred and forty-four growing Arbor acre broiler breeder pullets were used to determine the effect of vitamin E (dL-á-tocopheryl acetate; VE) on physiological and blood responses. The birds aged 21 days were randomly assigned to 4 treatments comprising 0, 50, 100, 150mgVE/kg of diet, with 3 replicates per treatment till day 84. Data obtained for rectal temperature (RT), heart rate (HR), respiratory rate (RR), skin temperature under wing (STW) and on the breast (STB), haematology and plasma biochemistry were subjected to analysis of variance. In female chickens, VE significantly (p<0.05) affected HR, STW, WBC, heterophil, lymphocyte and H/L ratio but did not affect RT, RR, STB, PCV, RBC, Hb concentration, eosinophil, monocyte, basophil, MCV, MCH, MCHC and biochemical parameters. Only pullets on 100mg/kg VE had lower HR than the control group. For STW, 50mg/kg VE had lower value than the control. VE, irrespective of dosage, increased (p<0.05) WBC and lymphocyte in pullets compared to control group. Except in 100mg/kg feed group, heterophil and H/L ratio in pullets on 50 and 150mg/kg feed recorded lower values than the control. VE administration of at least 50mg/kg in the diet of growing broiler breeder chickens might help in decreasing skin temperature, improving immunity and reducing stress under hot conditions.
Keywords: tocopherol; heat stress; broiler breeder; blood; haematology; plasma biochemistry