Dietary Intervention Of Vitamin A And Vitamin E On The Performance Of Isa Brown Laying Hens Under Heat Stress In The Humid Tropical Region Of Yandev, Benue State-Nigeria

This study was conducted at the Poultry Unit of the Department of Animal Health and Production Technology, Akperan Orshi Polytechnic, Yandev, Benue State – Nigeria to investigate the effects of supplemental Vitamin A (retinol) and Vitamin E (dl- alpha tocopheryl acetate) on performance parameters: hen day production, feed intake, feed conversion ratio, egg weight, haugh unit score, shell thickness, loss in body weight and mortality of Isa brown hens reared under the humid tropical conditions of Yandev, Benue State Nigeria. The study lasted for 24 weeks. A total of 160 twenty-week old Isa Brown pullets at the point of lay (POL) were vent examined and randomly divided into sixteen treatments of five (5) pullets per replicate and two such replicates constituted a treatment of ten (10) birds. Each experimental subject was randomly assigned to a thoroughly cleaned and disinfected cage measuring 49 x 35 x 42cm. Four dietary levels of Vitamin A: 0, 2000, 4000, and 6000IU Kg-1 basal diet were combined with four dietary levels of Vitamin E: 0, 125, 250 and 375mg Kg-1 basal diet in a 4 x 4 factorial arrangement in a Completely Randomized Design. Feed and water were supplied ad libitum. Results obtained indicated that hen day production, feed intake, feed conversion ratio, egg weight, shell thickness, and haugh units were highly significant (p < 0.01) among treatments and were better in vitamin treated hens than the controls. Loss in body condition, incidence of cracked eggs and mortality were significantly higher (p < 0.01) in the controls than vitamin supplemented birds. The combined effects of the vitamins A and E appear to be better than any of the vitamins used singly. These results hold that these 2- anti-oxidants, Vitamin A and E have synergetic effects, and have some protective roles against heat stress deleterious effects. Thus, dietary supplementation with 400mg Vitamin A plus 250mg Vitamin E per Kg of diet may increase egg production, improve egg quality and is economical in laying hens raised under heat stressed conditions.