IJADUNOLA, TAYE ISRAEL2025-12-112025-12-112024-10-20https://ir.funaab.edu.ng/handle/123456789/366A Thesis submitted to the World Bank Africa Centre of Excellence in Agricultural Development and Sustainable Environment, Federal University of Agriculture, Abeokuta in partial fulfillment of the requirements for the awards of degree of Doctor of Philosophy (PhD AgSE) in Monogastric Production.ABSTRACT Oxidative stress is an imbalance between prooxidants and antioxidants (in favour of prooxidants). Reactive oxygen species (ROS) are produced in the body continuously as a part of normal metabolism. However, when the defense system gets disturbed, there are adverse effects on the performance, product stature, health condition, survival, and overall welfare of poultry birds, and so requires an urgent dietary user-friendly strategy to curb. This study investigated the effects of dietary supplementation of selenium yeast, vitamin E and vitamin C on growth performance, nutrient digestibility, haematology, serum biochemical parameters, and carcass on oxidative stress induced by corticosterone hormone in Turkeys. A total of one hundred and twenty (120) BUT (British United Turkeys) day-old poults were assigned to 8 dietary treatments in a 4 x 2 factorial arrangement of 4 experimental diets containing no additive, Selenium-yeast(300mg/kg), vitamin C(200mg/kg), vitamins E(200mg/kg) each supplemented with or without corticosterone hormone (80mg/kg). A total of fifteen (15) turkeys were assigned to each treatment and replicated thrice with five (5) turkeys each. The results of this study revealed that without corticosterone better weight gain was recorded in the birds fed vitamin C. The feed conversion ratio was better in birds fed selenium yeast with 0 % corticosterone. The supplemented group without corticosterone showed significant (P<0.05) better live weight, bled weight, and Plucked weight. Packed cell volume (%), white blood cell (%) and Haemoglobin (g/dL) were significantly better in birds supplemented with vitamin E without corticosterone. In comparison to the control treatment, birds fed diets supplemented with Vitamin E and Vitamin C significantly increased serum levels of total protein and albumin under 80mg/kg corticosterone. However, additives of vitamin E, C and selenium did not show any significant effect for total protein and albumin. A significant increase in uric acid, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase and malondialdehyde (MDA) were observed for birds fed 80mg/kg corticosterone with additives. It can be concluded that inclusion of vitamin E, Vitamin C, and Selenium yeast with or without corticosterone supplement ensures the oxidative stability of turkeys with no adverse effect on growth and blood parameters.enThesis